feat: add functionality to reset branches

[Alieff]

Reset current branch to a commit highlighted by the cursor. I provided two kind of reset, 'soft' and 'hard'

• soft => the changes persist as unchanged file
• hard => no changes persist

[idbrii]

More notably, this isn't just equivalent to .reset --hard<CR> it also stashes the user's current changes and unstashes after the reset.

This isn't a workflow I use (I'd be making branches), but it's an interesting change.