fix: Replace unsupported code with placeholder

Author: twpol

Source/RunActivity/Viewer3D/Processes/WatchdogProcess.cs

@@ -276,6 +276,10 @@ internal void Step()
 
         StackTrace GetStackTrace()
         {
+#if NET5_0_OR_GREATER
+            // TODO: https://github.com/microsoft/clrmd is likely the best option to reimplement this in .NET 5+
+            throw new ThreadStateException("This is not implemented");
+#else
             // Yes, I know this is deprecated. Sorry. This code needs to collect the stack trace from a *different*
             // thread and this seems to be the only option - three seperate, deprecated APIs. :(
 #pragma warning disable 0618
@@ -289,6 +293,7 @@ StackTrace GetStackTrace()
                 Thread.Resume();
             }
 #pragma warning restore 0618
+#endif
         }
 
         bool StacksAreWaits()