Add "Reveal in Finder/Explorer" option on PR files

[miguelsolorio]

It would be great to get additional actions for PR files like Reveal in Finder/Explorer like in the SCM context menu. Right now the only option is "Open in GitHub" which isn't really useful.

[alexr00]

Hey @miguelsolorio! For modified files, we could do that. For added files when you don't have the PR checked out, we don't have the file available locally to reveal in the explorer.