GnssMetrics

These metrics will pull different metrics that tell the performance of the gnss subsystem.

Metrics include:
Location reports
% of location failure
Num times GPS had to first fix
Mean time to first fix on signal
Num position accuracy logs
Mean position accuracy in meters
Num top 4 Cn0 messages
Mean top 4 average Cn0 (signal quality)
Num L5 top 4 Cn0 messages
Mean L5 top 4 average Cn0 (signal quality)
Num Satellite status messages received
Num of Satellites used in fix
L5 Satellite status messages received
L5 of Satellites used in fix

metric_id: 1111
gauge_metrics {
  data {
    bucket_info {
      atom {
        gnss_stats {
          location_reports: 12
          location_failure_reports: 3
          time_to_first_fix_reports: 2
          time_to_first_fix_milli_s: 43588
          position_accuracy_reports: 9
          position_accuracy_meters: 112
          top_four_average_cn0_reports: 31
          top_four_average_cn0_db_mhz: 734711
          l5_top_four_average_cn0_reports: 1
          l5_top_four_average_cn0_db_mhz: 21500
          sv_status_reports: 1015
          sv_status_reports_used_in_fix: 100
          l5_sv_status_reports: 7
          l5_sv_status_reports_used_in_fix: 0
        }
      }
      elapsed_timestamp_nanos: 537249375445
      start_bucket_elapsed_millis: 522186
      end_bucket_elapsed_millis: 549283
    }
  }
}
time_base_elapsed_nano_seconds: 9283624934
bucket_size_nano_seconds: 60000000000
is_active: true

Bug: 147910698
Test: On Device using test script and gnsslogger.apk
>  make statsd_testdrive
>  ./out/host/linux-x86/bin/statsd_testdrive <ATOM_ID>

Change-Id: I92461eb8533ec810bb67d76a25931295cfa1efbd