feat: Add options for what to do with missing metadata fields in MetaFieldRanker

[robpasternak]

Related Issues

• fixes MetaFieldRanker: allow different options for what to do with missing metadata field #7691
• Adds param missing_meta to MetaFieldRanker:

        :param missing_meta:
            What to do with documents that are missing the sorting metadata field.
            Possible values are:
            - 'drop' will drop the documents entirely.
            - 'top' will place the documents at the top of the metadata-sorted list
                (regardless of 'ascending' or 'descending').
            - 'bottom' will place the documents at the bottom of metadata-sorted list
                (regardless of 'ascending' or 'descending').

Proposed Changes:

• The missing_meta param has three options: "bottom", "top", and "drop".
  • Using "bottom" exhibits the same behavior as was implemented prior to this PR, i.e., documents without the sorting metadata field are put on the bottom of the sorted list.
  • Using "top" puts them at the top instead.
  • Using "drop" drops such documents entirely.
• Validation was added to ensure that the value of missing_meta is legit.
• Tests were added for the new functionality.

How did you test it?

Wrote and tried new tests functions in the test directory:

• test_raises_value_error_if_wrong_missing_meta: Tests validation of missing_meta
• test_missing_meta_bottom: Tests that missing_meta = "bottom" behaves as desired.
• test_missing_meta_top: Tests that missing_meta = "top" behaves as desired.
• test_missing_meta_drop: Tests that missing_meta = "drop" behaves as desired.

Notes for the reviewer

None

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.
• I documented my code
• I ran pre-commit hooks and fixed any issue

[coveralls]

Pull Request Test Coverage Report for Build 9174873156

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.02%) to 90.57%

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Totals
Change from base Build 9129529675:	0.02%
Covered Lines:	6598
Relevant Lines:	7285

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💛 - Coveralls