Set the RTP Header Marker bit selectively per A2DP codec

Add a mechanism to set the RTP Header Marker bit per codec.
Currently, the Marker bit is set only for AAC.

Test: A2DP streaming, PTS AVDTP tests: TC_ACP_SRC_TRA_BTR_BV_01_C,
      TC_INT_SRC_SIG_SMG_BV_17_C, TC_INT_SRC_TRA_BTR_BV_01_C
Bug: 37723283
Change-Id: I9b8e77d44c750746c169df9628d5539ad2406b92