Small threading fix, delay to main thread

[rogerbarton]

Previously when calling a function on a worker thread and encountering a load error, setting the pause state would trigger a exception as we use the Unity API on a worker thread.

This is only for Lazy mode, where the thread safety is not yet fully implemented. But it still fixes this issue.

[mcpiroman]

So maybe just extract the dispatching logic to sth like:

void DispatchOnMainThread(Action action)
{
  if(Thread.CurrentThread.ManagedThreadId == _unityMainThreadId)
     action();
  else
     DllManipulatorScript.MainThreadTriggerQueue.Enqueue(action);
}

and use it both here and on previous PR

[rogerbarton]

Yes agreed. However, in the logic of the previous PR there's also an additional bool useMainThreadQueue:

UnityNativeTool/scripts/DllManipulator.cs

Lines 565 to 568 in f4eb21d

	if (useMainThreadQueue && Thread.CurrentThread.ManagedThreadId != _unityMainThreadId)
	DllManipulatorScript.MainThreadTriggerQueue.Enqueue(() => methodInfo.Invoke(null, args));
	else
	methodInfo.Invoke(null, args);

I've left it as is in the previous PR (seeing as its only one occurrence) and changed it for these diffs. Or do you see an nice way of doing this?

[mcpiroman]

Yup I forgot about that flag there. You could do something like this but I don't see much sense in doing so

if(useMainThreadQueue)
   DispatchOnMainThread(() => methodInfo.Invoke(null, args));
else
  methodInfo.Invoke(null, args)

so yes, leave this as is, whatever