GTK# is unstable, laggy, and somewhat broken under Windows

[ashifolfi]

This is a big issue for the engine tools framework which requires a toolkit that can be ran inside of an existing loop.

To my knowledge there's no way to run Avalonia in a way that allows me to manage the loop within the engine loop, rather the engine would be required to run within the Avalonia loop, which is unacceptable for how the engine functions.

We need to either rewrite the ImGui to allow for multiwindow, find a way to replace GTK# with something like Qt, or figure out how to fix the numerous performance issues GTK# suffers with Windows.