This adds support for the back paddles, and the "..." key
which are not automatically detected.
* "Back" is mapped to the top left "two windows" key.
* "Start" is mapped to the top right "hambuger menu" key.
* "Guide" is mapped to the "Steam" key.
* The "..." key is just a generic button.
When looking at the screen, paddles are number
* P1: Top right
* P2: Top left
* P3: Bottom right
* P4: Botom Left
The new controller mapping was created with the SDL3 gamepadmap tool.
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