Implement InputEventGesture (incl. Pan and Magnify) for all platforms

[akien-mga]

Operating system or device, Godot version, GPU Model and driver (if graphics related):
Current master (5a23136).

Issue description:
InputEventGesture was added to core in #12573, together with InputEventPanGesture and InputEventMagnifyGesture, but they're only implemented for macOS so far.

They should also be implemented for all platforms where they are relevant. I guess they would make sense on all platforms since gestures can be done on touchscreens as well as touchpads, so the list would be:

• Android (implement InputEventMagnifyGesture and InputEventPanGesture for android #25474 - reverted)
• iOS
• Web
• Wayland Linux and (if possible) *BSDs
• X11 Linux and (if possible) *BSDs
• macOS (Native pan and zoom for macOS + InputEventGesture #12573)
• Windows

See #12573 for the base API and its implementation on macOS.

If more types of gestures are wanted, they should likely be discussed in their own issue, let's keep this one focused on pan and magnify.

[raymoo]

Poor BSD, it doesn't even get its own checkbox.

[akien-mga]

Poor BSD, it doesn't even get its own checkbox.

Poor Linux, it has to share its checkbox.. All X11 platforms share the same code, so they can share the same checkbox.

[nathanfranke]

#25474 Merged, check Android box?

[Calinou]

@nathanwfranke Done.