Workspace <-> Namespace relationship

The following discussion from gitlab-org/cluster-integration/gitlab-agent!833 (merged) should be addressed:

• @cwoolley-gitlab started a discussion: (+5 comments)

  if we want to have a 1-many relationship between namespace-workspace, we can definitely go that direction if it makes sense.

  Keep in mind that this also adds additional data schema and logic requirements on the Rails side, since we will need to have an independent model + CRUD + relationships around namespaces instead of just assuming they are a property of the Workspace.

  We should definitely capture this as an issue, but consider the prioritization of it in relation to other important tasks.