[Gamepad overlays] Don't register analog stick movement on first touch

[DJM75]

Currently RetroArch registers the analog stick movement as soon as you place your finger in its hitbox area. This behaviour causes issues in many games, especially the ones where precise analog stick movements are required.

The analogue sticks in a touchscreen gamepad overlay should work as shown on the site I linked below (even remaining in a static position as it is now, but the first touch should only allow to "take control" of the analog stick without registering any movement):

https://developer.playcanvas.com/tutorials/touch-joypad/

To better understand what I mean, you can also give a look at this Lemuroid video I recorded (they are doing it right).

And here's a video of me playing "Super Mario 64" in RetroArch where you can see as in some areas precise analog stick movements are required and the issues I am talking about if the finger is not perfectly centered on the analog stick on first touch.