Add rollback parameters when submitting sessions to apexd.

This adds parameters to tell apexd if a session has rollback enabled,
or if it is a rollback. The rollback id is also included.

Previously in StagingManager, rollback was only enabled after the
session was submitted. This ordering is reversed in this change to
allow the rollback id to be retrieved.

For the 'is a rollback' case, a new InstallReason of INSTALL_REASON_ROLLBACK
is added, and the rollback id can be retrieved from RollbackManager.

This is an alternate approach to ag/9826517.

Bug: 141148175
Test: atest CtsRollbackManagerHostTestCases
Test: atest CtsStagedInstallHostTestCases
Change-Id: I560ee4ed6dd82277892a511909378d5a5a8502ff