backend-headless: add a seat and some devices
Clients like gtk depend on the wayland server providing a wl_seat. This adds one and also some dummy devices while at it.
This makes it possible to run the gtk test suite with the headless backend.
Clients like gtk depend on the wayland server providing a wl_seat. This adds one and also some dummy devices while at it.
This makes it possible to run the gtk test suite with the headless backend.