Introduce AttributionAndPermissionUtils.

The CameraService class is getting large and permission checking is
becoming a large portion of it. Separate this logic out into its own
utils class to make it easier to find code responsible for verifying
client permissions and the identity of the caller.

Bug: 190657833
Test: Smoke testof GCA, CtsCameraTestCases
Change-Id: I305706846db399eb92c8409271fb3e591539032f