[RMP] Set up unit tests for Merlin example notebooks

[jperez999]

All

• [Task] Test GPU Direct Storage with NVt NVTabular#222
• Link notebooks to containers in a way that makes it clear which container a given notebook will run on. #219

Merlin Models

• Fix for inappropiate cosine values NVTabular#226

Merlin Systems

• [DOC] Change criteo example notebook performance metric(s) and validate model NVTabular#225

Merlin

• [REVIEW] Creating dedicated loader submodule to build TF async dataloader NVTabular#224

[bschifferer]

Migrate the NVT example notebook unit tests to use Testbook

@EvenOldridge @rnyak @mikemckiernan Radek and me talked yesterday, if we need to restructure/move the NVTabular examples. The NVTabular example contains components, which are not relevant anymore (training, deployment). I am not sure, if it make sense to migrate the unittests to testbook, now. I think we should define the new structure, first and add the unittests for the notebooks which will stay and/or add the new unittests in the new repo (where they will move)

[EvenOldridge]

Now that the initial unit tests are in place we should come up with a process for adding new ones as examples are added to the libraries. @bschifferer can you work with me and @benfred to define this.