Fix csharpsquid:S1117 SonarCloud warnings about shadowing fields with variable names

[paulirwin]

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Fix csharpsquid:S1117 SonarCloud warnings about shadowing fields with variable names

Fixes #678

Description

This renames variables that shadowed fields of the same name, causing the SonarCloud S1117 warning. In the case of methods that replace static constructor initialization, this was named result instead of the field name. In other cases where there was no Lucene equivalent, the variable was renamed.

This also fixes a bug in FieldInfos where there was the possibility of a KeyNotFoundException due to a coding oversight.

This investigation discovered a potential maintainability bug in SortedSetDocValuesWriter.Flush. Due to GetOrdCountEnumerable and GetOrdsEnumerable (previously named with a typo) having the same return type, their names were accidentally swapped. I fixed the typo in the names and fixed the names to match upstream. I also confirmed that the signature of AddSortedSetField expected them in this order.

[paulirwin]

After reviewing the changes again, I don't think the SortedSet code was actually buggy, the methods were just misnamed which caused confusion. Having the correct names will help avoid confusion in the future.

[NightOwl888]

Thanks for the PR.

It looks pretty good, but there were 4 lines I think we should change before merging. Please see the inline comments.