Increase the Capability of Autotest & Add One More Feature to Fake Text

[donglihe-hub]

What does this PR do?

1. Add new dataset AmazonCat-13K
2. Add one more feature (lipsum) to the fake data
3. Allow val_size to be an integer larger than 10. Add new test parameters save_k_predictions and cluster_size.

Test CLI & API (bash tests/autotest.sh)

Test APIs used by main.py.

• [ ] Test Pass
  • (Copy and paste the last outputted line here.)
• [x] Not Applicable (i.e., the PR does not include API changes.)

Check API Document

If any new APIs are added, please check if the description of the APIs is added to API document.

• [ ] API document is updated (linear, nn)
• [x] Not Applicable (i.e., the PR does not include API changes.)

Test quickstart & API (bash tests/docs/test_changed_document.sh)

If any APIs in quickstarts or tutorials are modified, please run this test to check if the current examples can run correctly after the modified APIs are released.