Add AIDL interface and puller implementation for automotive devices.

Changes:
  - Adds hidden ICarStatsService AIDL API.
  - Adds CarStatsPuller for pulling atoms from ICarStatsService.
  - Pulls VmsClientStats via CarStatsPuller.

Bug: 141697665
Test: Manual testing on hawk using statsd_testdrive
Change-Id: I44e104d430f64b1bd3dce96e9749df79ab3d2fbf