Add bridge_features structure to bridge creation.  Specifically, this
implements mute and DTMF suppression, but others should be able to be
easily added to the same structure.

ASTERISK-27322 #close
Reported by: Darren Sessions
Sponsored by: AVOXI

Change-Id: Id4002adfb65c9a8027ee9e1a5f477e0f01cf9d61