[nocommit] LUCENE-9948: Automatically detect multi- vs. single-valued cases in LongValueFacetCounts

[gsmiller]

Description

Automatically detect single- vs. multi-value cases instead of asking the user to specify.

Solution

Use DocValues helper methods to automatically determine the underlying field type.

Tests

No new tests but modified existing to no longer require the multiValued ctor parameter, and ensured they cover both the single- and multi-valued cases.

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 created a Jira issue and added the issue ID to my pull request title.
• 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.

[rmuir]

looks good. thanks for cleaning up the api here.

[rmuir]

one TODO i want to try for fun, is to look at output from gradlew -p lucene/facet coverage and see if all the e.g. optimized cases here are really tested (#119). Will look into it later!

[rmuir]

Looks good: