camera2: Ensure SessionCharacteristics and CameraCharactersitics can

be used interchangeably

CameraDeviceSetup#getSessionCharacteristics documentation says that
the returned session characteristics can be used everywhere static
charactersitics from CameraManager#getCameraCharacteristics is.
However #getCameraCharacteristics sets up a few extra fields and
keys in the CameraMetadataNative object returned from cameraservice
that SessionCharacteristics was missing.

To make the return value of #getSessionCharacteristics completely on
par with the return value of #getCameraCharacteristics, this CL
ensures that #getSessionCharacteristics and #getCameraCharateristics
run the same logic on the CameraMetadataNative object returned from
cameraservice before returning it to the caller.

Bug: 303645857
Test: atest android.hardware.camera2.cts.CameraDeviceSetupTest
      passes
Change-Id: Ia7ac40c768480a39fe0d1dd9392b5777b0fc2694