libcamera_client: Add utils function isCameraServiceDisabled.

Note: ndk_vendor/ACameraManager.cpp is vendor code whcih can't depend on
a framework library without it being vndk, which libcamera_client isn't.

Bug: 168061412

Test: builds
Test: Camera app, native cts imagereader test(validity)

Change-Id: I87d8e056d0e8ef938d5c8f976417ca707d6471d9
Signed-off-by: Jayant Chowdhary <jchowdhary@google.com>