SurfacePackage: Add release method

Oversight, the SurfacePackage holds a reference to the SurfaceControl
which is protected by a close-guard. We need a way to close it
explicitly. Going to follow up with a patch to have SurfaceView
manage the lifetime when the SurfacePackage is consumed, but want
to make sure this explicit release gets in ASAP.

Bug: 149591513
Test: Existing tests pass
Change-Id: I7276a2440c38cc6d859b79b4c3ee57bc122ce2a6