Ignore [Experimental] overloads in MA0040 cancellation-token matching

[Copilot]

MA0040/MA0032 currently treats any matching CancellationToken overload as actionable, even when that overload is marked System.Diagnostics.CodeAnalysis.ExperimentalAttribute. This causes false positives by suggesting calls to APIs intentionally gated as experimental.

• Overload matching behavior

  • Extended OverloadOptions with IncludeExperimentalMembers (default false).
  • Updated OverloadFinder to detect ExperimentalAttribute and skip experimental methods unless explicitly included.
  • Result: MA0040 no longer reports based solely on experimental CancellationToken overloads.

• Regression coverage

  • Added SuggestOverloadWithExperimentalAttribute in UseAnOverloadThatHasCancellationTokenAnalyzerTests.
  • Test verifies no diagnostic is produced when the only CancellationToken overload is [Experimental].

Example covered by the new behavior:

public static void Method() { }

[Experimental("EXTEXP0001")]
public static void Method(CancellationToken cancellationToken) { }

// MA0040 should not suggest forwarding CT to Method() based only on this experimental overload.

Warning

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