Pipewire modifiers

Announce full capabilities wrt. hardware buffers via pipewire.

Probably works best with https://github.com/columbarius/obs-studio/tree/egl-modifiers.

Requires pipewire > 0.3.29

Requires firefox with https://bugzilla.mozilla.org/show_bug.cgi?id=1716747 merged.

Analog to https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1939?commit_id=36136cf3fee0457f50335350a147d231a61ec38c

cc: @apol @davidedmundson