[Proposal] Shortcut to copy selected file's path from file picker

[jabcross]

Apologies if this is already an existing feature.

When editing config files, a common use case is to search for a full file path and insert it. Since Helix already has a built-in file picker, it would he handy to have something like C-y to copy the selected entry's file path instead of just opening the file.

Keep in mind that the selected file is not necessarily a text file and you don't necessarily have read access to it, and so just opening it and using the % register may not be the best solution.