Make restoreSome API be @SystemAPI

Bug: 112292976
Test: atest RestoreSessionHostSideTest
Change-Id: Ic453be3ffed43a48839b3bcaf19438d9987eb201

RestoreSession#restoreSome is used from pixelmigrate to start a systemRestore
of packages selected by user, currently this needs to be done via reflection.
2 files changed