Handle WpLink errors
Add a new signal that gets emitted if any WpLink changes to an error state, and send client errors accordingly. This allows better error handling in cases where e.g. no format could be negotiated.
Together with pipewire!1534 (merged) closes pipewire#2935 (closed)
Required for https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2597
Supersedes pipewire!1503 (closed)
Edited by Robert Mader