SipHandler: fix call state reset, mic source, incoming RTP socket, my…

…Sdp syntax

- Reset callStarted/callStopped/currentCall at start of each call to
  prevent stale state from previous calls causing AudioRecord to open
  prematurely (confirmed by logcat: AudioRecord was opening 30s before
  200 OK due to callStarted=true from prior call)
- Use VOICE_CALL instead of VOICE_COMMUNICATION for AudioRecord source
  to avoid routing conflict with active voice call audio path (was
  capturing from call-speaker-mic instead of handset mic)
- Remove rtpSocket.connect() on incoming call RTP socket; sending a
  DatagramPacket with explicit address on a connected socket fails
- Fix missing closing ) on mySdp triple-quoted string (pre-existing
  upstream compile error)