Use ints instead of enum class to identify touch buttons

[alranel]

As of now, touch buttons are identified using an enum class:

Arduino_MKRIoTCarrier/src/Arduino_MKRIoTCarrier_Qtouch.h

Lines 29 to 35 in 4a894ad

	typedef enum {
	TOUCH0 = 0,
	TOUCH1,
	TOUCH2,
	TOUCH3,
	TOUCH4
	} touchButtons;

This means that in order to iterate over all the buttons to find out which one was pressed, a cast to the touchButtons type must be used:

for (int i = 0; i <= 4; ++i) {
   if (carrier.Buttons.onTouchDown((touchButtons)i)) {
      Serial.print("Button pressed: ");
      Serial.println(i);
   }
}

Considering this type is not documented anywhere and probably not strictly necessary, can't we just allow plan ints as arguments and get rid of those TOUCHx constants?