kmsbasertpendpoint: check if remote offer is rtcp-mux

Change-Id: I139a1e5d5056e026289059414cc46abe79c7cec7
kmsbasertpendpoint: add "proto" property

Change-Id: Ie6c49b9829469c74334434266fd20cce0b45e37a
kmsbasertpendpoint: improve addr_type management

Change-Id: Icaf4b16180332b735fc3eb904e162896dcfb1f97
kmsbasertpendpoint: add getters for local ssrcs

Change-Id: I78cc3b02f6623739aa5dac8b2c9174d92b084bfb
kmsbasertpendpoint: improve code

Change-Id: I502b7dd84ed6268cd378a79ae90cb964adf20205
kmsbasertpendpoint: use constants for rtcp-fb attrs

Change-Id: I9a2f9e30930068a6938bb615edb68e8643339cdc