Item A: Add messages to log profile connections
* Add ProfileUsageStats message in bluetooth.proto
* Add BluetoothProfileId enum to represent each profile
* Add num_times_connected item to log how many times a profile is
  connected

Item B: Add messages to log headset profile connections for HSP and HFP
* Add HeadsetProfileConnectionStats message in bluetooth.proto
* Add HeadsetProfileType enum to represent each headset profile type
* Add num_times_connected item to log how many times each headset
  profile is connected

* Add unit tests in metrics_tests
* Remove "clear" flag in various metrics dumping methods to make sure
  that we clean up metrics every time we dump

Bug: 77476285
Test: make, net_test_osi, BtFunhausMetricsTest,
      adb shell dumpsys bluetooth_manager --proto-bin
Change-Id: Ib18948c50ddb98ab7472f7b51a9bb98d153071c7
Merged-In: Ib18948c50ddb98ab7472f7b51a9bb98d153071c7

* Move bluetooth.proto to proto/ and compile it for both Java LITE
  runtime and C++ LITE runtime so that it can be shared between Java
  and native code
* Remove redundant comments in bluetooth.proto

Bug: 33693818
Test: make, toggle Bluetooth, clearcut server-client E2E test
      adb shell dumpsys bluetooth_manager --proto-bin
      ACTS tests: BtMetricsTest, BtFunhausMetricsTest
Change-Id: I7cd5e1b4fb8fcc197272ef8161ff384e53022424