Rollback user data of apks-in-apex while rolling back the apex

Currently, the RollbackManager is not aware of the apk-in-apex being
installed since the install is done by PM during scan phase of boot. As
such, RM does not backup the user data of the apk-in-apex.

In the new implementation, we ask the RM to snapshot/restore user data
of apk-in-apex while resuming the apex session in StagingManager.

Bug: 142712057
Test: atest StagedRollbackTest#testRollbackApexWithApk
Test: atest AppDataRollbackHelperTest
Test: atest RollbackStoreTest
Test: atest RollbackUnitTest
Change-Id: Ibbaa5d0c98cb883588c085d77bc89c3e8217d76a