Rollback for StepUnregisterApp

Rollback for StepUnregisterApp

Implement rollback operations for unregistering app.
Package should be fully restored in pkgmgr database
in case of failure of any subsequent step failures.

StepBackupManifest was changed to create copy of manifest
instead of moving it.

Original xml manifest file is used to
unregister application in StepUnregisterApplication and
is removed by uninstallation later.

Backup xml manifest file is used to restore package in
pkgmgr in case of rollback and is removed by StepBackupManifest
(this step is managing lifetime of backup file).

Change-Id: I51a055deb690425151d287262eed73d8b19acbf1