Refactor of camera stress test to add camera test helper. Also add

additional functional tests for: flash, exposure, white balance, and
focus mode.  Also add pairwise tests.

Slight refactor to add camera test helper and also additional
tests for: flash, exposure, white balance, and focus mode

Bug: 9174937

Change-Id: I3d26b545dc8ff972c8173066df59a2e572a837ef