Backend: Add `namespaces` to `scope` for Catalog resources query

Problem

As part of the CI Catalog Global search feature, we need to support a Your resources tab that shows resources from namespaces the user is a member of. For the first iteration, we must limit the scope to Public+Internal projects for performance reasons. Further details are explained in #429056 (comment 1641496694). --> No longer applicable, see #429056 (closed).

Proposed solution

UPDATE: Add a namespaces option to the ResourceScopeEnum. Update Catalog::Listing to accept the namespaces scope option and return all catalog resources (internal and public) for all namespaces that the user has access to. All access levels are included. All the public catalog resources that don't belong to a user's namespace should be filtered out.

Please use a feature flag to introduce this change and leave the FF in place until Backend: Improve CI Catalog `Your resources` qu... (#430885) is done.

Additional

• Revisit the usage of Ci::Catalog::Listing in app/graphql/resolvers/ci/catalog/resources_resolver.rb: !135017 (comment 1622177285)