If you create a NovelRT::Ecs::SystemScheduler as a variable which is then later initialised, this causes a crash

[dndn1011]

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Describe the issue: If you create a NovelRT::Ecs::SystemScheduler as a variable which is then later initialised, this generates no compile error or warnings, but the engine will fail due to conflicts caused by thread shutdown in the move function.

    SystemScheduler::SystemScheduler(SystemScheduler&& other) noexcept
        : _systemIds(std::move(other._systemIds)),
          _typedSystemCache(std::move(other._typedSystemCache)),
          _systems(std::move(other._systems)),
          _entityCache(std::move(other._entityCache)),
          _componentCache(std::move(other._componentCache)),
          _workerThreadCount(other._workerThreadCount),
          _currentDelta(other._currentDelta),
          _threadAvailabilityMap((1ULL << other._workerThreadCount) - 1),
          _shouldShutDown(false),
          _threadsAreSpinning(false)
    {
        if (other.GetThreadsAreSpinning())
        {
            other.ShutDown();
            SpinThreads();
        }
    }

I suspect it should not be shutting down the threads when the SystemScheduler is moved.

Please provide the steps to reproduce if possible:

1. Clone the repo
2. Go to a sample
3. Instead of initialising the scheduler directy with an initialiser, define the scheduler first and the assign to it:

   
   auto scheduler =
   Configurator()
   ...

|| V

NovelRT::Ecs::SystemScheduler scheduler; scheduler = Configurator() ...

4. Build and run 
5. Observe crash

**Expected behaviour:**
It should not crash in this case, or this use of SystemScheduler should be disabled.

**Please tell us about your environment:**  
N/A

**Additional context:**
I did attempt to remove the threads shut down in the move function, but this just resulted in a crash in ucrtbased with no useful stack information. I do wonder about there being two SystemScheduler s in existence briefly. One is constructed with its default constructor, and the second with arguments - I have a feeling that this is not intended behaviour or that if intended there is some contention between instances of system resources. I did try deleting the default constructor, but this caused compile issues elsewhere in the code.

I am working around this for now by simply putting SystemScheduler in a unique_ptr and initialising in one go with make_unique  

[RubyNova]

What's most likely happening is that its trying to stop threads from spinning that never started. When the scheduler moves it has to terminate any spinning threads because std::thread objects cannot be moved from what I recall, which creates a whole hassle of issues.

I'll look into it later today.