Add unit tests for TrxTestDefinitionName behavior in TrxReportEngine

[Copilot]

Addresses missing test coverage for the TrxTestDefinitionName property logic introduced to align UnitTest/@name in TRX files with test case display names rather than test result display names.

Tests added

• Explicit name used for UnitTest/@name: When TrxTestDefinitionName is present, UnitTest/@name uses it while UnitTestResult/@testName continues to use the node's display name.

• Duplicate id / conflicting explicit names throws: Two results sharing the same test id but carrying different explicit TrxTestDefinitionName values → InvalidOperationException.

• Ordering: fallback-first then matching explicit succeeds: First result has no TrxTestDefinitionName (falls back to display name); second result provides an explicit TrxTestDefinitionName equal to that fallback → no exception, dictionary updated to mark the entry as explicitly provided.

// First result: fallback name "MethodName"
CreateTestNodeUpdate("same-uid", "MethodName", new PropertyBag(new PassedTestNodeStateProperty()))
// Second result: explicit TrxTestDefinitionName "MethodName" — matches fallback, succeeds
CreateTestNodeUpdate("same-uid", "MethodName", new PropertyBag(new PassedTestNodeStateProperty(), new TrxTestDefinitionName("MethodName")))

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