Implements form submission for creating container protection tag rule

What does this MR do and why?

Implements form submission for creating container protection tag rule

• Adds submit & cancel button.
• Adds client side validations for input length on form submission.
• Calls create graphql mutation on form submit.
• Show error alert when mutation fails.
• Show toast when mutation succeeds.

Tests

• Adds fixtures for create mutation.
• Use fixtures for unit tests.
• Adds feature specs.

References

Please include cross links to any resources that are relevant to this MR. This will give reviewers and future readers helpful context to give an efficient review of the changes introduced.

• Previous MR which adds form: Adds form to add container tag protection rules (!177698 - merged)
• Designs:
  • Submit button: https://gitlab.com/gitlab-org/gitlab/-/issues/499871/designs/protected-container-tags.png
  • Server error: https://gitlab.com/gitlab-org/gitlab/-/issues/499871/designs/duplicate-tag-pattern.png
  • Inline error: https://gitlab.com/gitlab-org/gitlab/-/issues/499871/designs/error.png

MR acceptance checklist

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Screenshots or screen recordings

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Form	Server Error	Inline validation

How to set up and validate locally

1. Setup container registry.

2. Enable the metadata database https://gitlab.com/gitlab-org/gitlab-development-kit/-/blob/main/doc/howto/registry.md#metadata-database

   • Alternatively, you can apply the patch:

      diff --git a/app/helpers/packages_helper.rb b/app/helpers/packages_helper.rb
      index c35ad19155f6..ccad3b0c195e 100644
      --- a/app/helpers/packages_helper.rb
      +++ b/app/helpers/packages_helper.rb
      @@ -143,10 +143,7 @@ def settings_data(project)
          cleanup_settings_data(project).merge(
            show_container_registry_settings: show_container_registry_settings(project).to_s,
            show_package_registry_settings: show_package_registry_settings(project).to_s,
      -      is_container_registry_metadata_database_enabled: (
      -        show_container_registry_settings(project) &&
      -          ContainerRegistry::GitlabApiClient.supports_gitlab_api?
      -      ).to_s,
      +      is_container_registry_metadata_database_enabled: true.to_s,
            cleanup_settings_path: cleanup_image_tags_project_settings_packages_and_registries_path(project)
          )
        end

3. Enable feature flag

   Feature.enable(:container_registry_protected_tags)

4. Visit Project > Settings > Packages and registries.

5. Expand Container registry section

6. Create container registry protection rules & confirm validations & error messages are displayed.

7. Upon creation, confirm that the new rule is displayed in the table.

Related to #499871