Add: Acceptance test for module protocol

Should be able to use negative class expressions with classes defined from
module protocol right away.

ref: https://dev.cfengine.com/issues/6689
I know I said ``test_suppress_fail`` at first, but please use ``test_soft_fail`` instead. The semantics are slightly different, and this prevents the test case from showing up as a regression or platform error in the test metrics.

Also, I assume this will fail everywhere, so you should using ``any`` class expression instead of ``linux``.