Fixes winit applications getting a wl_shm_pool protocol error
Longer explanation: It seems if you immediately change a winit window's decoration mode after it binds xdg-decoration then winit no likey and it requests a shm buffer with 0 width leading to a protocol error. If the decoration window rule is applied earlier this doesn't happen
While this initial implementation is done and I'm pretty happy with it, there are still 2 problems:
1. The cursor is not warped to the hinted position when a locked pointer constraint is removed. This may require an update to Smithay to expose a `PointerConstraintsHandler::constraint_removed` method.
2. The cursor may jump between two close constraint regions if it's moved fast enough. This can be fixed by possibly doing a ray cast or something.
Extracts the dummy output name into a const. Unfortunately I still need a way to interpolate that into Lua strings. Also fixes possible hangs when Lua crashes
