p2p: add proto for P2P metrics

Add P2P metrics listed below:
* general information
  * the number of scanning
  * saved persistent groups
* p2p connection
  * connection type: fresh/reinvoke/local
  * connecting time
  * failure reason
* p2p group
  * channel used
  * group role
  * connected clients
  * session duration
  * idle duration

Bug: 119998319
Test: collect bugreport to check metrics
Test: Unit Test - atest frameworks/opt/net/wifi/tests/wifitests
Change-Id: I921398fae5a77b7ce7f72e555b423972ef2fcef3