Add ID field to app platform resources

[alexander-akhmetov]

Adding a computed ID field to the app platform base Resource model. This field is required with by the current testing framework version for acceptance tests.

The field is computed and should not result in a plan change. Tested locally:

1. Created a new grafana_apps_playlist_playlist_v0alpha1 resource
2. Applied it with the old provider version and checked the state: no id field

terraform state show 'grafana_apps_playlist_playlist_v0alpha1.test_playlist'

# grafana_apps_playlist_playlist_v0alpha1.test_playlist:
resource "grafana_apps_playlist_playlist_v0alpha1" "test_playlist" {
    metadata {
        uid     = "tf_test_playlist"
        uuid    = "D2tQoZxmFNLHZ55sHDzaooxGV97VxtexXNl9nDE2E8sX"
        version = "1757057965719"
    }
    options {
        overwrite = true
    }
    spec {
        interval = "1h"
        items    = [
            {
                type  = "dashboard_by_uid"
                value = "ed155665"
            },
        ]
        title    = "[tf] Test Playlist"
    }
}

3. Updated the provider version and ran the plan again:

terraform plan

...
No changes. Your infrastructure matches the configuration.

Terraform has compared your real infrastructure against your configuration and found no differences, so no changes are needed.

[github-actions]

In order to lower resource usage and have a faster runtime, PRs will not run Cloud tests automatically.
To do so, a Grafana Labs employee must trigger the cloud acceptance tests workflow manually.

[radiohead]

Looks great! Just a small note about using UUID instead of UID.