kvm/test: Improve sanity check

Calling makeModuleSetUpAndTestCaseClass results already with preparing some
environment and also test classes will run the promises, so they would never
execute test_kvm_sanity_check.

So create a method sanityCheck to check the environment and depending of the
result call or not makeModuleSetUpAndTestCaseClass and skipIf test cases
when environment is not sane enough.