Changes

trau2rtp CSD: add option to emit TW-TS-007 payloads

Setting OSMO_RTP_EXT_TWTS007 bit in st->rtp_extensions switches
CSD RTP output format from standard but inefficient CLEARMODE to
the compressed-CSD RTP payload format of TW-TS-007.  This new
mechanism is fully symmetric with already implemented mechanism
that enables or disables TW-TS-001 and TW-TS-002 RTP output
for FR/HR/EFR speech codecs.

Depends: I2cc2c9340f9fa5c7111447a6beef49c335fa1107 (libosmocore)
Change-Id: I86d628c65104a119ef0fb9f27f5835c9a1769971