No "Undo" and "Redo" buttons in piano roll

Dear Developers:
Could you add "Undo" and "Redo" buttons in piano roll. I think it's much easier to write music, when you're knowing, that your actions are reversible.))))

The issue names no files, entry points, or tests. Start by locating the piano roll implementation and any existing undo/redo handling, then determine how the requested controls should connect to it; done means the piano roll exposes working Undo and Redo buttons that reverse and restore user actions.

Written by the indexing model from the issue text.