Geo: UX improvements on admin panel for uploads

The initial implementation for the Geo admin panel for uploads was implemented in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/9720. But there are some things that can use some improvements.

Proposed changes

• Clickable headers, so you can visit the upload.
  • While at it, a link to the same file on the primary node would be nice too (using the external icon)
• Show to which "model" an upload belongs to. Now that field is only shown when it's a project. But it also can be a snippet...
• Make it possible to filter project too
• Add bulk actions to sync everything that's e.g. Failed.
• Show updated_at instead of created_at timestamp -> https://gitlab.com/gitlab-org/gitlab-ee/issues/10957
• Impossible to delete orphaned registry through Admin -> https://gitlab.com/gitlab-org/gitlab-ee/issues/11017