LUCENE-10550: Add getAllChildren functionality to facets

[Yuti-G]

Description

This new API returns all children for a specified path and allows users to sort in their desired criteria

Solution

• Added getAllChildren function in the Facets class.
• Override getAllChildren in subclasses

Tests

Added new testing for all the overridden implementations of getAllChildren in Facets

Checklist

Please review the following and check all that apply:

• I have reviewed the guidelines for How to Contribute and my code conforms to the standards described there to the best of my ability.
• I have given Lucene maintainers access to contribute to my PR branch. (optional but recommended)
• I have developed this patch against the main branch.
• I have run ./gradlew check.
• I have added tests for my changes.

[gsmiller]

Thanks @Yuti-G! Excited to see this getting implemented. I ran out of time today to look at your approach to testing, but left you some feedback on the main implementation. Thanks again!

[Yuti-G]

Thanks @gsmiller for spending time reviewing my PR and leaving the great feedback! I addressed all of the comments except for the one that requires casting List<Integer> to int[] for ordinals to call getBulkPath in the IntTaxonomy and FloatTaxonomy. Please let me know if there is a better way to do it. Thanks!

[gsmiller]

Thanks! Changes look good to me. Left one small comment on javadoc. Also, could you please add an entry to the CHANGES.txt file? From what I can tell, this should be a fully backwards-compatible change, so we should be able to put it in the 9.3 section and back-port. Please let me know if you have questions on adding the CHANGES entry, or questions about back-porting. Thanks again!

[Yuti-G]

Thank you so much for the last check! I added more javadoc and a new entry to the CHANGES.txt. For back-porting, should I wait until this PR is merged and checkout a new branch against the latest branch_9x to cherrypick the merged commit? Thanks again!

[gsmiller]

For back-porting, should I wait until this PR is merged and checkout a new branch against the latest branch_9x to cherrypick the merged commit? Thanks again!

Exactly! Then you can open a PR with that branch against origin/branch_9x (github will automatically select origin/main as the suggested destination so just change that). And just mention that it's a backport PR.

[gsmiller]

Merged onto main. Thanks again @Yuti-G! Exciting to see this new functionality available :)