[Fix] add HkvHashTableExportWithScores op

[jq]

Description

Fix missing HkvHashTableExportWithScores op with help/collaborate from @MoFHeka and zhiheng

Fix the incompatiblity with new tf.keras.optimizers.Adagrad, it pass 0 shape tensor during the init, and we fix it by init with 0 Reduce the default buffer_size of FileSystemSaver to 4k

Brief Description of the PR:

Fixes # (issue)

Type of change

• [ ] Bug fix
• [ ] New Tutorial
• [ ] Updated or additional documentation
• [ ] Additional Testing
• [ ] New Feature

Checklist:

• [ ] I've properly formatted my code according to the guidelines
  • [ ] By running yapf
  • [ ] By running clang-format
• [ ] This PR addresses an already submitted issue for TensorFlow Recommenders-Addons
• [ ] I have made corresponding changes to the documentation
• [ ] I have added tests that prove my fix is effective or that my feature works

How Has This Been Tested?

If you're adding a bugfix or new feature please describe the tests that you ran to verify your changes: