chore: move alpha resources to stable provider

[nunoadrego]

In this PR, we move alpha resources into the stable releases. We are not promoting the resources to stable - this is a change in how we structure the provider.

From now on:

• Alpha resources will be included in the stable build.
• Alpha builds will be less frequent - only for internal testing. Customers will mostly use stable builds.

Benefits:

• Terraform provider docs will include all resources (stable and alpha).
• Customers won't need to switch between stable and alpha builds to test new resources in the alpha state.

[nunoadrego]

/test production