feat: add controller support for pause menu and update ImGuiLayer functionality

include/panda_sdl/frontend_sdl.hpp

@@ -64,6 +64,11 @@ class FrontendSDL {
 	bool keyboardAnalogY = false;
 	bool emuPaused = false;
 	bool returnToSelector = false;
+	#ifdef IMGUI_FRONTEND
+	bool controllerStartHeld = false;
+	bool controllerSelectHeld = false;
+	bool controllerPauseComboArmed = true;
+	#endif
 
   private:
 	void setupControllerSensors(SDL_GameController* controller);

include/panda_sdl/imgui_layer.hpp

@@ -27,6 +27,7 @@ class ImGuiLayer {
 	void setPauseCallback(std::function<void(bool)> callback) { onPauseChange = std::move(callback); }
 	void setVsyncCallback(std::function<void(bool)> callback) { onVsyncChange = std::move(callback); }
 	void setExitToSelectorCallback(std::function<void()> callback) { onExitToSelector = std::move(callback); }
+	void showPauseMenuFromController();
 
   private:
 	void drawDebugPanel();