session: handle transport setup correctly
session: handle transport setup correctly

Handle UDP, MCAST and TCP transport negotiation more correctly.
Store the server session SSRC in the transport.

barisdemiray/gst-rtsp-server,thaytan/gst-rtsp-server,surround-io/gst-rtsp-server,surround-io/gst-rtsp-server,hsteinhaus/gst-rtsp-server,Lachann/gst-rtsp-server,thaytan/gst-rtsp-server,barisdemiray/gst-rtsp-server,Lachann/gst-rtsp-server,hsteinhaus/gst-rtsp-server,thaytan/gst-rtsp-server,hsteinhaus/gst-rtsp-server,surround-io/gst-rtsp-server,Lachann/gst-rtsp-server,barisdemiray/gst-rtsp-server