joystick: add xbox controller SVG

[ES-Alexander]

I started this branch a couple of weeks ago, and don't remember what state it was in (possibly semi-working, but not fully with the button highlighting?), so I'll need to test it again before it's ready for review (and correcting any incorrect button mappings, since I don't have the hardware to test with).

Built off https://github.com/bluerobotics/cockpit/issues/1927#issuecomment-3191735822.