The server sets the spatial layer, rid, ssrc and repair ssrc of each
video layer from SDP and RTP. Clear these fields on AddTrack request
layers, including each simulcast codec's layers.
Clamp the layer in ReceiverBase.SetMaxExpectedSpatialLayer to
[InvalidLayerSpatial, DefaultMaxLayerSpatial].
Keep a client set video layer mode, but warn when it differs from the
server determined mode.
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>