Allow rebinding Cmd key on a Mac

[eugenesvk]

As far as I understand, this is a complete list of all supported keybinds https://github.com/prompt-toolkit/python-prompt-toolkit/blob/master/src/prompt_toolkit/keys.py. It doesn't have Cmd key even though some terminals support passing it to the shell (e.g., via some https://sw.kovidgoyal.net/kitty/keyboard-protocol, not sure whether there are more comprehensive alternatives)

Am I correct that PTK currently doesn't support Cmd key and to enable it it would also have to explicitly add support for some kind of extra protocol? Or is there a simple way to rebind everything already today :)?