Handle native undo/redo

[luin]

Currently, our editor listens on the common hotkeys (cmd+z / cmd+shift+z) for undo/redo but the user could always undo using native browser UI like right-click, the edit topbar menu, and on mobile iOS there is a toolbar, and the native undo usually does not do the right thing.

Most modern browsers support using beforeinput to interrupt native undo/redo inputs so we'll use this to handle them natively. Firefox supports this event since v74 but hasn't enabled it by default.

To test:

• Insert some text, make some chars bold.
• Click Undo in the context menu, make sure the chars are unbold. Click undo again should remove the text.
• For Firefox, it should behave the same as before.

[Dedrus]

I tried to handle native undo redo click in our electron app(we are using quill, thanks for your work), and saw you PR.
@luin I'm almost sure that due to prevent default there will be no redo option after you clicked undo, because event will not reach stack of commands
https://discuss.prosemirror.net/t/native-undo-history/1823 this discussion covers this case a bit

[luin]

@Dedrus Thanks for bringing this up. Actually I tried something pretty similar to the provided link when working on this PR and generally I think the idea works but would require more work on it, whereas the scope of this PR was to prevent potential issues caused by native events.

Anyway, I think it's worth revisiting this for better undo/redo stack handling.