[Enhancement] Force windowed mode by default

[originalnicodr]

Describe the new feature or enhancement

Some games don't give you the option to play them on windowed mode to allow us to hotsample. However, this can be fixed with the following launch parameters:

-screen-fullscreen 0 -popupwindow

I can include them in the documentation for people to use, but it would be great if we could actually enforce them from within CUE (and maybe let people turn it off in the settings).

We should be able to use Screen.fullScreen for the first parameter, but I don't have any idea if I can call the second one programmatically with Unity API. This is all of what I could find.