nuklear_xcb: no text input

[beatwise]

Demo's input boxes don't show any text when pressing keys:

xcb_key_symbols_get_keysym always returns 0. Probably, it's because kp->state is not a valid argument for its third parameter "col".

[riri]

Would you make a PR about this?

[beatwise]

I have no fix for this. It's pretty involved: https://github.com/iplinux/xcb-util/blob/master/keysyms/keysyms.c#L110

There's an easier way: libxkbcommon - https://xkbcommon.org/doc/current/md_doc_2quick-guide.html