Currently, every time compositing is restarted, both the gbm and the egl streams backend will re-obtain the EGLDisplay object. This is wrong because the core assumption is that the EGL display doesn't change once it has been obtained.
We should not assume that the cursor capabilities are shared by all DRM devices.
This commit sets up udev and the DrmBackend to list and use all GPUs. BUG: 425586 BUG: 417323