[Input] [Windows] Limit for-loop to the 14 actually available buttons for XInput

[MJacred]

See https://learn.microsoft.com/en-us/windows/win32/api/xinput/ns-xinput-xinput_gamepad#members.

Note: marking as draft, as I'd like to test on Windows first. Just in case.

[Calinou]

Tested locally on Windows 11 24H2 (rebased on top of master 71d80b2), this breaks the X/Y buttons on a wired Xbox Elite Series 2 controller which aren't recognized anymore. Other buttons work correctly.

[MJacred]

Thanks for testing! Not sure why this happens… Looking at the buttons in that list, they mostly overlap with Godot's JoyButtons, except for JOY_BUTTON_GUIDE, which xinput doesn't provide. While that could explain X or Y not working. But both of them puzzles me right now.
I have a few busy weeks ahead, afterwards, I'll look into this again