Metrics: Add classic pairing metrics

* Log HCI commands and events related to classic pairing
* Move all metrics logging for sending HCI command into a single
  function
* Move all metrics logging for HCI command status into a single function
* Move all metrics logging for HCI Command complete into a single
  function
* Move all metrics logging for HCI events into a single function
* Make sure we log all instances of HCI command sending methods,
  including those with desinated callbacks

Bug: 112969790
Test: make, testdrive with statsd
Change-Id: I4b1ca4ee814096d84bcd93c8d7206b0a771a3210