PBAP: Use PbapStateMachine to handle new connection

Move the connection socket part in PbapService to PbapStateMachine.

PbapService handles the following tasks:
 - implementing service lifecycle methods
 - starting and stoping the server socket
 - managing SDP records and PbapUtils
 - handling broadcast from Bluetooth PBAP permission request
 - handling broadcast from PBAP OBEX challenge request
 - managing wakelock
 - implementing the PbapBinder interface

PbapStateMachine (new) handles the following tasks:
 - sending and getting Bluetooth PBAP permission request to and from
 PbapService
 - sending and getting PBAP OBEX challenge request to and form
 PbapService
 - using PbapObexServer to handle PBAP OBEX requests
 - maintaining the connection status

 The Bluetooth PBAP permission request is handled by Settings; the PBAP
 OBEX challenge request is handled by BluetoothPbapActivity.

Bug: 70939570
Test: carkits with PBAP
Change-Id: I77ebb7f64370326b717db64cb94c8696f74b0c5c