chore(sonar): hoist constant array literals to static readonly fields (CA1861)

Applied via `dotnet format analyzers --diagnostics CA1861 --severity info`,
plus manual cleanup:

- Renamed two cryptic fixer-generated field names:
  - QueryBreakdownCollection.stringArray -> SnowflakeFunctionNames (and
    inlined the now-redundant local alias)
  - ExpressionObjectTests.arg2 -> NotInValues
- Deduped three identical `separator = ['\r','\n']` fields the fixer
  emitted in the same test class (kept the first declaration; the other
  two test methods now reuse it).

8 files touched.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/Strata.SqlTools.LinqToSql.Tests/LinqQueryBreakdownTests.cs

@@ -7,6 +7,7 @@ namespace Strata.SqlTools.LinqToSql.Tests;
 public class LinqQueryBreakdownTests
 {
     private TestDataContext _context = null!;
+    private static readonly string[] separator = new[] { "AND" };
 
     [SetUp]
     public void Setup()
@@ -303,7 +304,7 @@ public class LinqQueryBreakdownTests
         Assert.That(filterSql, Does.Contain("IsActive = 1"));
 
         // Should have multiple AND conditions
-        var andCount = filterSql.Split(new[] { "AND" }, StringSplitOptions.None).Length - 1;
+        var andCount = filterSql.Split(separator, StringSplitOptions.None).Length - 1;
         Assert.That(andCount, Is.GreaterThanOrEqualTo(2));
     }