* changes:
Use "commit" instead of "execute" for rollbacks.
Rename PACKAGE_ROLLBACK_EXECUTED to ROLLBACK_COMMITTED.
Remove unused RollbackManager APIs.
Use RollbackManager.getAvailableRollbacks in RollbackTest
Use new RollbackManager API in RollbackPackageHealthObserver.
Add RollbackManager.getAvailableRollbacks API.
Include all relevant packages in RollbackInfo.