Typed actor annotations

[devholic]

Background

#1872 introduces kargo.akuity.io/create-actor to track who created the given resource.

As @hiddeco pointed out in #1872 (review), we may want to add contextual information to the annotation.

Suggestions

• Use JSON encoded typed value instead of an actor string

  {
    "actor": "subject:some-user",
    "controlplane": false
  }

  • controlplane field is to indicate whether the resource is created by controlplane (or we can leverage prefixes like this)

• Introduce kargo.akuity.io/last-update-actor to track who updated it

  • We may merge create/update actor into single annotation (kargo.akuity.io/actor), but I think it's more clear to have separate annotations and it gives us more flexibility when we decided to change annotation structure.

    {
      "created-by": {...},
      "last-updated-by": {...}
    }

Note

• We should consider that other MutatingWebhooks may affect the typed information
  • Adding type check in validating webhook will be helpful