[pm] add package installer session metrics

BUG: 418283971
FLAG: EXEMPT adding metrics
Test: manual with following steps
1. m statsd_testdrive
2. statsd_testdrive 1101
3. install an app on the device
4. check the output of statsd_testdrive:

atom {
        1101: {
          1: 924330694 // session_id
          2: 0
          3: 0
          5: 4294967295 // -1
          6: 2
          7: 0
          8: 5242994 // install_flags
          9: 1
          10: 0
          11: 0
          12: 0
          13: 18446744073709551615 // -1L
          14: 0
          15: 1
          16: 0
          17: 1
          18: 0
          19: 0
          20: 0
          21: 0
          22: 0
          23: 1
          24: 0
          25: 3 // success
          26: 0
          27: 0
          28: 781 // session_idle_duration_millis
          29: 2882 // session_commit_duration_millis
          30: 99 // native_libs_extraction_duration_millis
          31: 1930 // package_verification_duration_millis
          32: 847 // internal_installation_duration_millis
          33: 3663 // session_lifetime_duration_millis
        }

Change-Id: I228fb05c4d73e89a2a3368b797b8b0d6a5fce10d