Part of dapr#1172

Adds hot reloading functionality to Daprd, which is gated behind the HotReload preview feature.

If enabled, Daprd in Selfhosted mode will watch for resource updates
from watching the resource directory(s). If a resource is detected as
changed (spec is different to what is currently loaded), then Dapr will
close/create/update the resource.

Supports Component _except_ HTTP middlware which requires further
changes to the HTTP server handler machinery. A warning is thrown if hot
reloading is enabled and a HTTP middleware is updated.

The hot reloader reconciler is made generic to enable other resource
types to be added in future.

---

When running in standalone mode, the disk loader watches the directories
passed by --resources-path for updates to yaml files containing
Components.

When an event occurs, the reconciler and differ are responsible for
determining whether any resources have been created, updated, or
deleted, by comparing the local store specs with that of the remote. If
any have changed, the resource is closed (if it exists), and then
re-initialized (if it exists). A resource will only be closed if it has
been deleted, only initialized if it has been created, and closed &
initialized if it has been updated.

We consider a resource to have changed generally if anything apart from
its Kubernetes metadata or type meta object meta has changed, and
therefore needs some kind of reloading.

---

Currently, if a reloading component errors and `spec.ignoreErrors=false`
then Daprd will gracefully close, like a component loaded at startup
today. It is intended that in future the component will be re-inited on
a backoff queue in future in the case of errors, even if
`spec.ignoreErros=true`.

HTTP middleware component hot reloading is not supported as it requires
further changes to the HTTP server handler machinery, and I didn't want
to grow this PR further.

To use the HotReloading feature, which is currently only available as an
alpha feature in Selfhosted mode, users need to add the following
Configuration to the target Daprd;

```yaml
apiVersion: dapr.io/v1alpha1
kind: Configuration
metadata:
  name: hotreloading
spec:
  features:
  - name: HotReload
    enabled: true
```

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

each event

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Part of dapr#1172

Adds hot reloading functionality to Daprd, which is gated behind the HotReload preview feature.

If enabled, Daprd in Selfhosted mode will watch for resource updates
from watching the resource directory(s). If a resource is detected as
changed (spec is different to what is currently loaded), then Dapr will
close/create/update the resource.

Supports Component _except_ HTTP middlware which requires further
changes to the HTTP server handler machinery. A warning is thrown if hot
reloading is enabled and a HTTP middleware is updated.

The hot reloader reconciler is made generic to enable other resource
types to be added in future.

---

When running in standalone mode, the disk loader watches the directories
passed by --resources-path for updates to yaml files containing
Components.

When an event occurs, the reconciler and differ are responsible for
determining whether any resources have been created, updated, or
deleted, by comparing the local store specs with that of the remote. If
any have changed, the resource is closed (if it exists), and then
re-initialized (if it exists). A resource will only be closed if it has
been deleted, only initialized if it has been created, and closed &
initialized if it has been updated.

We consider a resource to have changed generally if anything apart from
its Kubernetes metadata or type meta object meta has changed, and
therefore needs some kind of reloading.

---

Currently, if a reloading component errors and `spec.ignoreErrors=false`
then Daprd will gracefully close, like a component loaded at startup
today. It is intended that in future the component will be re-inited on
a backoff queue in future in the case of errors, even if
`spec.ignoreErros=true`.

HTTP middleware component hot reloading is not supported as it requires
further changes to the HTTP server handler machinery, and I didn't want
to grow this PR further.

To use the HotReloading feature, which is currently only available as an
alpha feature in Selfhosted mode, users need to add the following
Configuration to the target Daprd;

```yaml
apiVersion: dapr.io/v1alpha1
kind: Configuration
metadata:
  name: hotreloading
spec:
  features:
  - name: HotReload
    enabled: true
```

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Branched from dapr#7239

Part of dapr#1172

Adds hot reloading functionality to Daprd, which is gated behind the HotReload preview feature.

If enabled, Daprd in Kubernetes mode will watch for Component resource
updates from the Operator. If a resource is detected as changed (spec is
different to what is currently loaded), then Dapr will
close/create/update the resource.

Supports Component _except_ HTTP middlware which requires further
changes to the HTTP server handler machinery. A warning is thrown if hot
reloading is enabled and a HTTP middleware is updated.

---

When running in Kubernetes mode, the operator loader streams updates from
the Operator API. When an event occurs, the event type will trigger the
resource to be created, updated, or deleted. Updated components will be
closed, and then re-initialized.

We consider a resource to have changed generally if anything apart from
its Kubernetes metadata or type meta object meta has changed, and
therefore needs some kind of reloading.

---

Currently, if a reloading component errors and `spec.ignoreErrors=false`
then Daprd will gracefully close, like a component loaded at startup
today. It is intended that in future the component will be re-inited on
a backoff queue in future in the case of errors, even if
`spec.ignoreErros=true`.

HTTP middleware component hot reloading is not supported as it requires
further changes to the HTTP server handler machinery, and I didn't want
to grow this PR further.

To use the HotReloading feature, which is currently only available as an
alpha feature in Selfhosted mode, users need to add the following
Configuration to the target Daprd;

```yaml
apiVersion: dapr.io/v1alpha1
kind: Configuration
metadata:
  name: hotreloading
spec:
  features:
  - name: HotReload
    enabled: true
```

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Part of dapr#1172

Adds hot reloading functionality to Daprd, which is gated behind the HotReload preview feature.

If enabled, Daprd in Selfhosted mode will watch for resource updates
from watching the resource directory(s). If a resource is detected as
changed (spec is different to what is currently loaded), then Dapr will
close/create/update the resource.

Supports Component _except_ HTTP middlware which requires further
changes to the HTTP server handler machinery. A warning is thrown if hot
reloading is enabled and a HTTP middleware is updated.

The hot reloader reconciler is made generic to enable other resource
types to be added in future.

---

When running in standalone mode, the disk loader watches the directories
passed by --resources-path for updates to yaml files containing
Components.

When an event occurs, the reconciler and differ are responsible for
determining whether any resources have been created, updated, or
deleted, by comparing the local store specs with that of the remote. If
any have changed, the resource is closed (if it exists), and then
re-initialized (if it exists). A resource will only be closed if it has
been deleted, only initialized if it has been created, and closed &
initialized if it has been updated.

We consider a resource to have changed generally if anything apart from
its Kubernetes metadata or type meta object meta has changed, and
therefore needs some kind of reloading.

---

Currently, if a reloading component errors and `spec.ignoreErrors=false`
then Daprd will gracefully close, like a component loaded at startup
today. It is intended that in future the component will be re-inited on
a backoff queue in future in the case of errors, even if
`spec.ignoreErros=true`.

HTTP middleware component hot reloading is not supported as it requires
further changes to the HTTP server handler machinery, and I didn't want
to grow this PR further.

To use the HotReloading feature, which is currently only available as an
alpha feature in Selfhosted mode, users need to add the following
Configuration to the target Daprd;

```yaml
apiVersion: dapr.io/v1alpha1
kind: Configuration
metadata:
  name: hotreloading
spec:
  features:
  - name: HotReload
    enabled: true
```

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>

Signed-off-by: joshvanl <me@joshvanl.dev>