kiosk-shell: bind key to weston surface

weston surface displays on fullscreen mode with kiosk shell, multiple surfaces overlap each other when running client applications on the same output monitor. This is to bind a key to an application's weston surface, then it's able to display this specific surface on monitor top level via sending an activate keyboard event to it.

usage: set a key to an application app-id in weston.ini app-ids=org.freedesktop.weston.transformed:a,org.freedesktop.weston.simple-egl:b

run application weston-transformed and weston-simple-egl, press 'Alt+a' and 'Alt+b' to switch display between these two applications.

Signed-off-by: Sophia Gong lili.gong@amd.com