Add deterministic NativeAOT regression smoke test for GC restricted reverse P/Invoke assert path

[Copilot]

This adds a focused NativeAOT regression test for the GC restricted callout path where background GC can invoke managed [UnmanagedCallersOnly] callbacks and hit Thread::InlineTryFastReversePInvoke assertion behavior prior to the runtime fix. The change is test-only and is intended to reliably drive the failing pre-fix path, not modify product behavior.

• Test added

  • src/tests/nativeaot/SmokeTests/GcRestrictedCalloutReversePInvoke/
  • New smoke test project plus program harness.

• Repro wiring

  • Registers tracker support via ComWrappers.RegisterForTrackerSupport(...).
  • Creates a tracker object through MockReferenceTrackerRuntime so GC restricted tracker callbacks are active (GCStopCollection path).

• Deterministic triggering

  • Forces repeated concurrent Gen2 collections (GC.Collect(..., blocking:false)).
  • Runs bounded allocation pressure on a background thread.
  • Uses timeout + synchronization (SpinWait + elapsed bound) instead of unbounded probabilistic loops.

• Scope/guards

  • Configured as process-isolated NativeAOT smoke test.
  • Excludes Apple mobile and Android targets where the required native dependency is not available in this leg.
  • Keeps coverage broad otherwise (not win-x86-only).

• Expectation documented

  • Source comment references dotnet/runtime#110683 and states expected behavior:
    • release: test should complete,
    • assertion-enabled runtime (before product fix): can fail on the target assertion path.

• Environment limitation observed while validating command

  • In this environment, Release NativeAOT targeted test build failed due to missing Microsoft.DotNet.ILCompiler.SingleEntry.targets; Checked configuration was used for targeted execution.

GC.Collect(2, GCCollectionMode.Forced, blocking: false, compacting: false);

if (GC.GetGCMemoryInfo().Generation == 2 &&
    GC.GetGCMemoryInfo().Concurrent)
{
    // Concurrent Gen2 observed while tracker GC callbacks are registered.
    // This is the targeted repro envelope for dotnet/runtime#110683.
}

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