msc: add sdp to MNCC

SDP is added to the MNCC protocol in osmo-msc
Ie16f0804c4d99760cd4a0c544d0889b6313eebb7.
This patch adds SDP to the ttcn3 MNCC messaging.

These changes still work with current osmo-msc master that doesn't send SDP /
ignores received SDP in MNCC.

Change-Id: Ic9568c8927507e161aadfad1a4d20aa896d8ae30
3 files changed