Hotload: Implement upgrader for interface instances

[MuffinTastic]

Putting this in Game.cs...

public interface ITest
{
    public string TestProperty { get; set; }
}

public class TestImplementation : ITest
{
    public string TestProperty { get; set; }
}

public class Game : BaseGame
{
    // ...

    private ITest _instance;

    public override void Startup()
    {
        // ...

        _instance = new TestImplementation();

        // ...
    }

    // ...
}

... and then triggering a hotload by saving the file again results in this, and leaves the field/property null.

[xezno]

Fixed with https://github.com/xezno/mocha/commit/1cd0ef74d585b77c586e57cec2fd7231bb026f05