[Mono] need to skip tests failed with PlatformNotSupportedException

I was testing roslyn testcase on ppc64le and we got few test cases failed with PlatformNotSupportedException. I have investigated and found EXCEPTION POINTERS are not supported on MONO runtime. And resulting to fail testcaes with PlatformNotSupportedException.

Exception is thrown from here. https://github.com/dotnet/runtime/blob/803afaad000d84bef1625b1659dd9d97f66c83de/src/mono/System.Private.CoreLib/src/System/Runtime/InteropServices/Marshal.Mono.cs#L92

        public static IntPtr GetExceptionPointers()
        {
            throw new PlatformNotSupportedException();
        }

The Dispose() function from Roslyn calls the GetExceptionPointers from here. https://github.com/dotnet/roslyn/blob/e7cae311ab49148335e969b94fb47f0dffaa95df/src/Test/PdbUtilities/EditAndContinue/EditAndContinueTest.cs#L192C9-L203C10

        public void Dispose()
        {
            // If the test has thrown an exception, or the test host has crashed, we don't want to assert here
            // or we'll hide it, so we need to do this dodgy looking thing.
            var isInException = Marshal.GetExceptionPointers() != IntPtr.Zero;

            Assert.True(isInException || _hasVerified, "No Verify call since the last AddGeneration call.");
            foreach (var disposable in _disposables)
            {
                disposable.Dispose();
            }
        }

We need to skip these tests. I could not find the way to skip tests for mono runtime in roslyn. However, I have tried the [ConditionalFact(typeof(ClrOnly))] for skipping the test but it didn't work.

Is there any way in roslyn to skip tests those are not supported on mono.

Example:

$ dotnet --info
.NET SDK:
 Version:           8.0.100
 Commit:            57efcf1350
 Workload version:  8.0.100-manifests.e15fffd0

Runtime Environment:
 OS Name:     ubuntu
 OS Version:  20.04
 OS Platform: Linux
 RID:         linux-ppc64le
 Base Path:   /home/ubuntu/vikas/debugger/output_release/.dotnet/sdk/8.0.100/

.NET workloads installed:
 Workload version: 8.0.100-manifests.e15fffd0
There are no installed workloads to display.

Host:
  Version:      8.0.0
  Architecture: ppc64le
  Commit:       5535e31a71

.NET SDKs installed:
  8.0.100 [/home/ubuntu/vikas/debugger/output_release/.dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 8.0.0 [/home/ubuntu/vikas/debugger/output_release/.dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 8.0.0 [/home/ubuntu/vikas/debugger/output_release/.dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
  None

Environment variables:
  DOTNET_ROOT       [/home/ubuntu/vikas/debugger/output_release/.dotnet]

global.json file:
  /home/ubuntu/vikas/roslyn/global.json

Learn more:
  https://aka.ms/dotnet/info

Download .NET:
  https://aka.ms/dotnet/download

Steps to Reproduce:

1. $ cd src/Compilers/CSharp/Test/Emit2
2. $ dotnet test --filter FullyQualifiedName=Microsoft.CodeAnalysis.CSharp.EditAndContinue.UnitTests.EditAndContinueStateMachineTests.AsyncMethodOverloads

Backtrace:

Stack trace:
[xUnit.net 00:03:42.14] Microsoft.CodeAnalysis.CSharp.EditAndContinue.UnitTests.EditAndContinueStateMachineTests.AsyncMethodOverloads [FAIL]
  Failed Microsoft.CodeAnalysis.CSharp.EditAndContinue.UnitTests.EditAndContinueStateMachineTests.AsyncMethodOverloads [87 ms]
  Error Message:
   System.PlatformNotSupportedException : Operation is not supported on this platform.
  Stack Trace:
     at System.Runtime.InteropServices.Marshal.GetExceptionPointers()
   at Microsoft.CodeAnalysis.EditAndContinue.UnitTests.EditAndContinueTest`1[[Microsoft.CodeAnalysis.CSharp.EditAndContinue.UnitTests.EditAndContinueTest, Microsoft.CodeAnalysis.CSharp.Emit2.UnitTests, Version=42.42.42.42, Culture=neutral, PublicKeyToken=31bf3856ad364e35]].Dispose() in /home/ubuntu/vikas/roslyn/src/Test/PdbUtilities/EditAndContinue/EditAndContinueTest.cs:line 196
   at Microsoft.CodeAnalysis.CSharp.EditAndContinue.UnitTests.EditAndContinueStateMachineTests.AsyncMethodOverloads() in /home/ubuntu/vikas/roslyn/src/Compilers/CSharp/Test/Emit2/Emit/EditAndContinue/EditAndContinueStateMachineTests.cs:line 681
   at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)