webrtcbin: ability to specify preferred audio/video codecs

Looking at https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/blob/45a1070203a39246a693ce5f0a14f5984ec1df30/ext/webrtc/gstwebrtcbin.c#L1497-1551

I thought it would be possible to set codec_preferences on a transceiver, but it doesn't seem to be (at least from Rust bindings).

Would be really nice though to be able to specify caps for transceiver on receiving side if sender provided a list of possible codecs, as browsers usually do, to prefer some codecs over others.