Help users associate workspaces with the right repos

[iaindillingham]

With #4574, it's even easier for a user to associate a workspace with the wrong repo (jobserver.views.workspaces.WorkspaceCreate). Having done so, a user can't associate the workspace with the right repo.

We should consider how to help a user associate a workspace with the right repo.

[iaindillingham]

We discussed this issue during today's Team REX planning meeting and decided not to work on it now. We considered:

• Filtering the list of repos
• Making improvements to the UI
• Displaying validation warnings rather than validation errors
• Allowing a user to edit the association, at least until the first job request was submitted

We didn't feel there was a quick fix, so accepted that some users will create workspaces that are associated with the wrong repos, and will then have to archive those workspaces and start-over.