Metrics: Add Bluetooth address obfuscator

* Add an address obfuscator that takes a 256-bit randomly generated
  salt and hashes a Bluetooth MAC address using HMAC-SHA256 algorithm
* The salt is generated per Android device during the first time
  Fluoride native layer is initialized after a connectivity reset
* The output of the above operation is an unique identifier for a
  Bluetooth device on the same Android device, but yet remains
  anonymous across different Android devices.
* Add a logging method loghex(std::array) that allows dumping integral
  arrays into a hex string
* Add more error logging to btif_config_get_bin() so that we know why it
  fails in the future
* Change mutex in btif_config to recursive_mutex to avoid deadlock when
  calling btif_config API functions with API function

Bug: 112969790
Test: mm -j40, bluetooth_test_common
Change-Id: I11f01cc82fe805c97fd7c86ad83b3d324ee5af53