Add metrics for audio codec during voice calls

Expand existing Telephony metrics to include information on the codec
used during voice calls, including also all renegotiation of the audio
codec during a voice call.

Bug: 119871674
Test: Verified dumping metrics after several calls on CS and IMS
Change-Id: I8e763fdb5428d983fec20bb1f0d9dafbbdf6ad4f