Hotkey version 3

[theinterned]

This is a tracking issue for hotkey version 3 which will introduce a few breaking changes:

Some of this was split from #65

### Tasks
- [ ] https://github.com/github/hotkey/pull/66
- [ ] https://github.com/github/hotkey/issues/93
- [ ] https://github.com/github/hotkey/pull/94
- [ ] https://github.com/github/hotkey/issues/92
- [ ] https://github.com/github/hotkey/issues/69
- [ ] https://github.com/github/hotkey/issues/54
- [ ] https://github.com/github/hotkey/issues/68
- [ ] https://github.com/github/hotkey/issues/45

[turgs]

👋 @theinterned Is there a timeframe for when v3 will be available?

[theinterned]

Hi @turgs. Sorry I missed this earlier.

Unfortunately, I haven't been focused on hotkey recently so I don't have any timelines at the moment.

[theinterned]

@turgs just a heads up that v3 is under active development and we are working to ship many of the changes documented here

[iansan5653]

Created v3 branch to compile these changes