socket_pair: send and receive RTCP packets

This patchset allows to send RTCP packets.
Ice callbacks are used to read RTP and RTCP packets.
Synchronisation mechanism is added between libav reading callbacks
and ice callbacks

Issue: #78983
Change-Id: Iafef224551fec1d2794b0ef3b2ee885d9ca75fb5
Signed-off-by: Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>