Factor window scale in UserInputManager.mouseOutsideAllDisplays

[Susko3]

The mouse position is in pixel/client coordinates, while window and displays positions are in window coordinates.

Proof of coordinate spaces for display position (on a 3456x2234 macbook):

(Image taken from https://discord.com/channels/188630481301012481/188630652340404224/1308162379045011506)

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We should probably have IWindow.ClientToDisplay(Vector2) that takes in a client (game screen space) vector and converts it to display coordinates. Would the need for ISDLWindow type checks from this code.

[frenzibyte]

We should probably have IWindow.ClientToDisplay(Vector2) that takes in a client (game screen space) vector and converts it to display coordinates. Would the need for ISDLWindow type checks from this code.

We already have PointToClient/PointToScreen but those are unimplemented on non-Windows platforms (and they heavily lack documentation and clarification on how they even work, and there's also this which is funny at this point).

[frenzibyte]

Auto merge is borked (android CI is dead and it's marked as required), to be manually merged by anyone.