Start using the media subscriptions model
(based on newly introduced `media_subscription` objects)
in scope of:
- `redis_encode_json()`
- `json_link_medias()`
- `rbl_subs_cb()`
Change-Id: I3f7267ab156b361d7e7bec4ff91a8976a7be02ee
Transcoding is flow-specific, so it doesn't make sense to have a flag
for it in a call_media section. Instead we use the transcoding flag set
on the call_subscription objects (on subscribers), and set/unset a flag
on the monologue struct, depending on whether any media flows (going to
subscribers) have transcoding enabled.
Change-Id: Id671d56e56a22eaa8e56f6d449770b0c7b086cea
We're also in controlling role for subscribe answers.
Make sure we don't clobber the source media's ICE options when adding a
subcriptions.
Change-Id: I5361462aefdbbe6411841332b69a8dc4b0e1e013