Surface who locked files better

Problem

The current implementation of locking files doesn't show who locked it, this is only discoverable in a separate context /path_locks (example)

Proposal

Depends on Common directory and blob page structure changes (&13018) being completed.

Display the details of the user who locked the directory/file.

• Popover title: Locked by {firstname lastname} {time of lock}
• User details because we display that user information elsewhere in GitLab whenever showing user information.