frontend: Enable uncloned repo count on cloud

Created by: ryanslade

This was disabled in the past because it was slow, this change takes a different approach where we first list their affiliated external services and use that to filter down their repos before joining with the new gitserver_repos table to check clone state.

For normal users it counts any repos added by external services they own.

For admin users it also inclued repos added by ANY site level external service, apart from our default GitHub and GitLab repos since they're cloned on demand.