Fixed bug 5466 - Add haptic support for Stadia Controller

Dimitriy Ryazantcev

Consider adding support for Stadia Controller haptics.

Here is example code how to deal with it:
https://github.com/chromium/chromium/blob/99314be8152e688bafbbf9a615536bdbb289ea87/device/gamepad/hid_haptic_gamepad.cc#L45

include/SDL_hints.h

@@ -663,6 +663,17 @@ extern "C" {
  */
 #define SDL_HINT_JOYSTICK_HIDAPI_PS5_PLAYER_LED "SDL_JOYSTICK_HIDAPI_PS5_PLAYER_LED"
 
+/**
+ *  \brief  A variable controlling whether the HIDAPI driver for Google Stadia controllers should be used.
+ *
+ *  This variable can be set to the following values:
+ *    "0"       - HIDAPI driver is not used
+ *    "1"       - HIDAPI driver is used
+ *
+ *  The default is the value of SDL_HINT_JOYSTICK_HIDAPI
+ */
+#define SDL_HINT_JOYSTICK_HIDAPI_STADIA "SDL_JOYSTICK_HIDAPI_STADIA"
+
 /**
  *  \brief  A variable controlling whether the HIDAPI driver for Steam Controllers should be used.
  *