Basic gamepad support through SDL (#407)

* Add basic gamepad support through SDL

* lightbar, vibration, code style changes

* okay fine

* one day clang format will finally pass

src/sdl_window.h

@@ -7,6 +7,7 @@
 #include "common/types.h"
 
 struct SDL_Window;
+struct SDL_Gamepad;
 union SDL_Event;
 
 namespace Input {
@@ -66,6 +67,9 @@ public:
 private:
     void onResize();
     void onKeyPress(const SDL_Event* event);
+    void onGamepadEvent(const SDL_Event* event);
+
+    int sdlGamepadToOrbisButton(u8 button);
 
 private:
     s32 width;