editor: react on Enter, Tab, and Up-Down arrow keys
editor: react on Enter, Tab, and Up-Down arrow keys

The editor will now insert new lines and tabulations when
pressing the corresponding keys on the virtual keyboard.

The Up and Down arrows can be used to navigate through
lines.

Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=77496

Signed-off-by: Manuel Bachmann <d58f3f53462d5b02b85dbad407eeedd70c66c30c@open.eurogiciel.org>

Fantu/compositor-spice,giucam/weston,udoprog/weston,mchalupa/weston,kwm81/weston,eyolfson/weston,mchalupa/weston,jonnylamb/weston,Tarnyko/weston-xdg_surface_present,xorgy/weston,udoprog/weston,Tarnyko/weston-xdg_surface_present,kwm81/weston,Gnurou/weston,Gnurou/weston,krezovic/weston,Fantu/compositor-spice,giucam/weston,sir-murray/weston,jonnylamb/weston,Fantu/compositor-spice,krezovic/weston,sir-murray/weston,xorgy/weston,eyolfson/weston