Use Yjs UndoManager

[dmonad]

Undo/Redo doesn't work correctly anymore because remote changes are ignored by the UndoManager (see #8 ). When y-monaco is used, we should use Y.UndoManager instead of Monaco's UndoManager.

[raedle]

@dmonad, I pushed a change to my forked y-monaco GitHub repo which adds the Y.UndoManager. It seems to work with two clients (see screencast). However, a few tests are now failing. Any suggestion what I broke? :)

Happy to submit a PR if you think the code is ok and tests pass

Screencast with Y.UndoManager

y-monaco-undo-manager.mp4

[alexkreidler]

Any update on this?