wayland: DMABuf modifier support using feeback

Colin Kinloch requested to merge ColinKinloch/gstreamer:dmabuf_feedback into main

Implement explicit modifier for DMABuf in waylandsink using zwp_linux_dmabuf v4 (feedback).

Previously by setting the drm-device property the user could copy video frames to dumb buffers.
In this branch drm-device is set automatically to a device provided via main_device therefore this feature can now be enabled using the dumb-buffer-copy property.

This is reduced from the changes here which excludes DMABuf feedback for wl_surfaces, backwards compatibility with implicit modifiers and some refactoring of show_frame.

CC: @He_Junyan, @rmader, @ndufresne

Edited by Colin Kinloch

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