DRM leasing

This patch allows the compositor to offer connectors up for lease so that clients can use them directly by implementing https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/67. As the protocol pretty much has to be merged into wayland-protocols to be used by client implementations (especially for the Vulkan extension) merging this should wait until that's done.

The design of the API is so that the DRM objects that are leased (except the actual connector) can be changed by the compositor until an actual lease is granted. This makes it easy to re-assign crtcs and planes as necessary.