Complete AutoEncoder mojo

[wendycwong]

Support ticket: https://support.h2o.ai/a/tickets/107055

We have deeplearning mojo working. However, it is not clear if AutoEncoder mojo is working properly. Hence, this assignment will be to do two things:

1. Make sure autoencoder mojo works. If not, fix it;
2. Work with MLOPs team to make sure it works in MLOPs. Properly needs to work with MLOPs team to complete this one.

[maurever]

The Deeplearning MOJO has already been implemented, and the autoencoder mode is also available.

Associated PRs:
#1497
#6249

We have tests for Deeplearning Autoencoder in Java, R, and Python. Everything seems ok.

I also run this test:
https://github.com/h2oai/h2o-3/blob/master/h2o-py/tests/testdir_javapredict/pyunit_pubdev_4628_pubdev_4950_deeplearning_mojo_pojo_autoencoder_NOPASS.py

It failed for the first time because the h2o.import_file function returned one more column for deep-learning mojo output., which is strange. But other prediction results are ok. After I removed the last column from the imported file, the test passed. I am still investigating this strange behavior.

cc: @wendycwong

[wendycwong]

[wendycwong]

[maurever]

@wendycwong I only found a bug when using PredictCSV with autoencoder, see this PR: #16013. Otherwise, everything works.