test that verifier success implies generator success
test that verifier success implies generator success

Summary:
We raise errors during signature generation when we encounter something unexpected. Ideally these
errors would already be raised by signature verification. By running all successful verification
tests through the generator and checking for success, we can have some confidence in the soundness
of the verifier, and can guard against regressions where the verifier is relaxed on some case
without correspondingly handling that case in the generator.

Reviewed By: panagosg7

Differential Revision: D10118499

fbshipit-source-id: fa687b3df636cb44d4425acbbd2f840590d0e5cc

nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow