Metrics: Log pairing state change to statsd

* Log bond state transition and failure reasons
* Log pin request and replies
* Loig SSP confirmation request and replies

Bug: 112969790
Test: make, test drive with statsd
Change-Id: I2b201645ca071ac368c7914b1e52e6d8e1bc400b
Merged-In: I2b201645ca071ac368c7914b1e52e6d8e1bc400b