FPHSA: Convert FOUND_VAR failure test to RunCMake

Move the Tests/FPHSA_InvalidFOUND_VAR test case over to a new
RunCMake.FPHSA test with a BadFoundVar case.  The RunCMake tests are
built to cover failure cases easily and robustly.
Merge topic 'FPHSA_FOUND_VAR_OPTION' into next

8a1f13c FPHSA: Convert FOUND_VAR failure test to RunCMake