Restrict tag rule operations when the Gitlab API is not supported

In this MR, we want to block creating, updating, and deleting ContainerRegistry::Protection::TagRule when the GitLab API is not supported (i.e. the container registry is not migrated)

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How to set up and validate locally

Prerequisite: The GitLab API is supported when you have the next generation container registry running.

ContainerRegistry::GitlabApiClient.supports_gitlab_api? # => true

1. When the GitLab API is supported:

current_user = User.first # this is root or you can also set it to your account
project = Project.last # make sure that current_user has privileges on project

::ContainerRegistry::Protection::CreateTagRuleService.new(project, current_user, {tag_name_pattern: 'samplestring', minimum_access_level_for_push: :admin, minimum_access_level_for_delete: :admin}).execute

Success when creating:

=> #<ServiceResponse:0x00000001631950a0
 @http_status=:ok,
 @message=nil,
 @payload=
  {:container_protection_tag_rule=>
    #<ContainerRegistry::Protection::TagRule:0x000000016305ccd8
     id: 14,
     project_id: 28,
     created_at: Wed, 22 Jan 2025 06:44:15.926600000 UTC +00:00,
     updated_at: Wed, 22 Jan 2025 06:44:15.926600000 UTC +00:00,
     minimum_access_level_for_push: "admin",
     minimum_access_level_for_delete: "admin",
     tag_name_pattern: "asasa">},
 @reason=nil,
 @status=:success>

2. When the GitLab API is NOT supported:

ContainerRegistry::GitlabApiClient.supports_gitlab_api? # false

::ContainerRegistry::Protection::CreateTagRuleService.new(project, current_user, {tag_name_pattern: 'samplestring', minimum_access_level_for_push: :admin, minimum_access_level_for_delete: :admin}).execute

Error when creating:

=> #<ServiceResponse:0x0000000162996890
 @http_status=nil,
 @message="Feature is only available for migrated container registries",
 @payload={:container_protection_tag_rule=>nil},
 @reason=nil,
 @status=:error>

Related to #506402