input manager provides ground of truth on device input choise

lib/input_manager.cpp

@@ -27,6 +27,18 @@ InputManager::InputManager(LowLevelTouch* touch, const GameConfig* config)
     : touch(touch), config(config) {
 }
 
+bool InputManager::has_touch() const {
+    return touch != nullptr;
+}
+
+bool InputManager::has_buttons() const {
+#ifdef BUTTON_KEY0_PIN
+    return true;
+#else
+    return false;
+#endif
+}
+
 InputEvent InputManager::process_touch_input(uint32_t* last_time) {
     InputEvent event = {INPUT_NONE, 0, 0, 0, 0, 0, false};