Log apexd reverts to StatsLog

When resuming sessions in StagingManager, check whether any
apex sessions have an associated crashing native process, which
indicates the session has been reverted by apexd. Keep track of
this failure reason (there will be only one), and the one or more
package names which have been reverted. Wait until the BOOT_COMPLETED
broadcast (which needs to occur to know that StatsLog is ready) before
logging through WatchdogRollbackLogger.

Only log once per logging parent package, in the case that multiple
packages with the same parent have been reverted.

Test: atest WatchdogRollbackLoggerTest
Test: atest ApexRollbackTests#testAutomaticBootLoopRecovery, check
      logcat to ensure revert is being correctly logged
Bug: 138782888

Change-Id: I57999260a826e476e0a75abe1304a83768b4c819