rtpsession: Call on-new-ssrc earlier
Right now, we may call on-new-ssrc after we have processed the first RTP packet. This prevents properly configuring the source as some property like "probation" are copied internally for use as a decreasing counter. For this specific property, it prevents the application from disabling probation on auxiliary sparsed stream.
Probation is harmful on sparsed streams since the probation algorithm assume frequent and contiguous RTP packets.
I'd like some input, do you think this is an ABI break ? Would be rather ugly to have to introduce a new signal for this. I haven't found anything that depends on the fact that at least one RTP packet was queued. The reason is that the SSRC might be created elsewhere, because it was seen inside an RTCP report.