Extended Keyboard Input Support

[migueldeicaza-msft]

There is a proposal floating around to extend the keyboard support in terminals:

https://sw.kovidgoyal.net/kitty/keyboard-protocol.html

It allows things like reporting on the status of additional key modifiers, as well as distinguishing individual keystrokes.

Might be worth adding.

[migueldeicaza]

Work in progress branch:

https://github.com/migueldeicaza/SwiftTerm/compare/main...extended-keyinput

[migueldeicaza]

This is how tmux implemented it:

0ab82d95314e7a26a48452c77ad710f3aff97dd7