Implement longValues for MultiFieldNormValues to speedup CombinedQuery

[HUSTERGS]

Description

This PR Implements longValues method for MultiFieldNormValues to speedup CombinedQuery
Here is the luceneutil benchmark result with wikimediumall and searchConcurrency set to 0, after 20 iterations:

                            TaskQPS baseline      StdDevQPS my_modified_version      StdDev                Pct diff p-value
                    CombinedTerm       10.04      (8.2%)       12.49     (11.1%)   24.5% (   4% -   47%) 0.000
             CombinedAndHighHigh        5.00      (7.6%)        6.32     (12.6%)   26.3% (   5% -   50%) 0.000
              CombinedOrHighHigh        4.99      (7.9%)        6.30     (12.6%)   26.4% (   5% -   50%) 0.000
              CombinedAndHighMed       17.08      (8.0%)       22.87     (12.5%)   33.9% (  12% -   59%) 0.000
               CombinedOrHighMed       16.90      (8.2%)       22.76     (12.7%)   34.7% (  12% -   60%) 0.000

[github-actions]

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[jpountz]

This looks good to me, can you add a comment that this code relies on the assumption that document lengths can never be equal to 0?

[HUSTERGS]

The lastest nightly benchmark catch up with this change, and shows about 15% speedup on Combined type queries
https://benchmarks.mikemccandless.com/2025.10.10.20.23.06.html