[Feature Request] Add ability to compare everything: branches, worktrees, local directories, etc..

[ablekhman]

Often I need to compare:

• two arbitrary branches, both can be local, remote, or mixed case;
• a branch (either local or remote) vs local directory;
• two local directories (can be git worktrees, or copies of a repo);
• two tags (either local or remote);
• etc...

I would like to be able to select various items in UI and diff between them.

There is branch comparison via Cmd+Click (on MacOS). However, it works only with local/checked out branches. If I select two remote branches, then no diff shown.