[openfga] Allow specifying custom annotations in all manifests

[PedroArvela]

There are several use cases where custom annotations are required. For example, we are currently adding automatic database credential rotation in our deploy using Reloader, as well as scraping only some (but not all) of the Prometheus metrics using Datadog. Both of these require custom annotations both in the deployments and pods of the release.

Currently, only ingresses and pods support custom annotations. Instead of adding support for each specific annotation that might be useful, the proposal is to add support for defining annotations that can be added to all resources or to the pods specifically, allowing any of these use cases to be solved the same way.