ipc: add xkb_layout_names and xkb_active_layout_index
ipc: add xkb_layout_names and xkb_active_layout_index

These can be useful to implement per-window layouts as a script.

See https://github.com/swaywm/sway/issues/2361

ascent12/sway,SirCmpwn/sway,1ace/sway,ascent12/sway,1ace/sway,1ace/sway,ascent12/sway