Currently we allow tests to be "waived" by a param 'waived' in FactoryTest item (i.e., test list).

However, when a test item is 'waived', it'll pass for no matter reasons, including syntax error or segv in execution in pytest.

We've found in recent build that there may be cases "we want to waive particular item".

One example: the touchscreen wants to collect uniformity data and in early builds and fail in PVT/MP builds. As a results, they want a test that

 - Try to collect data (and fail if that part failed)
 - Compare data with known configuration
 - Waive in early builds if data don't match, and fail in late builds.
   (This can be configured by a factory test param)

As a result, in additional to the assertXXXX or ui.Fail calls, we'd like to get a new function like ui.Waived.