Implement new templates to publish OpenTofu modules and providers to the GitLab Container Registry (OCI)

The goal of this issue is to implement new templates to publish OpenTofu modules and providers to the GitLab Container Registry (an OCI registry).

Prerequisites:

• OpenTofu media type support in the registry, see Support new OpenTofu media types in container r... (#562714 - closed)

Implementation Plan

• Add type input to the module-release template with a supported value of regular and oci, where oci publishes to the GitLab Container Registry instead of the Terraform modules registry.
• Add new provider-release template to publish OpenTofu providers too the GitLab Container Registry.

Draft implementation at: components/opentofu!370 (merged)