Automatically change Fullscreen to Borderless when in the workshop menu

This stems from an issue @CalculatorSpoon was having in the Discord. Basically, when exclusive fullscreen is being used, and a model upload dialog box is opened, because of how exclusive fullscreen works, the game hangs. This would be easily fixed by either forcing players using exclusive fullscreen into borderless or windowed when using workshop, or just having a warning that the game may crash when using exclusive fullscreen.