Option to constrain mouse cursor to game window

[Clorf]

Right now if you use mouse gyro it's very easy for the mouse cursor to get flung outside of the game window, where it can cause trouble if it lands on the wrong part of the taskbar in Windows.

There should be an option to constrain or disable the cursor if Dusk is the active Window. That or it should be the default or only behavior.

[Irastris]

Planning to address this during #1011

[Irastris]

While there is no ETA on when it will be merged into main and included in a release build, this is now included in my mouse PR (#1011), so I'm going to go ahead and close the issue