RemoteDesktop: Send damage rects for each frame sent via PipeWire
As already noted in https://gitlab.gnome.org/jadahl/gnome-remote-desktop/-/merge_requests/7#note_822052 and gnome-control-center#212 (comment 380066), mutter currently does not send damage rects alongside the frames sent via PipeWire.
This is rather unfortunate since sending damage rects will allows us in g-r-d to have to encode less data and to have to transfer less data over the network.
Both effects can also improve the remote desktop performance (especially with RDP when the server has to send raw (compressed) bitmaps because the client doesn't support any codecs (* cough* Remmina with default options, Vinagre, g-boxes)) as the data amount (which we send) can be reduced by a huge amount.