input_common: Add property to invert an axis button

src/input_common/input_engine.cpp

@@ -58,6 +58,8 @@ void InputEngine::SetHatButton(const PadIdentifier& identifier, int button, u8 v
 }
 
 void InputEngine::SetAxis(const PadIdentifier& identifier, int axis, f32 value) {
+    value /= 2.0f;
+    value -= 0.5f;
     {
         std::scoped_lock lock{mutex};
         ControllerData& controller = controller_list.at(identifier);

src/input_common/input_poller.cpp

@@ -939,6 +939,7 @@ std::unique_ptr<Common::Input::InputDevice> InputFactory::CreateAnalogDevice(
         .threshold = std::clamp(params.Get("threshold", 0.5f), 0.0f, 1.0f),
         .offset = std::clamp(params.Get("offset", 0.0f), -1.0f, 1.0f),
         .inverted = params.Get("invert", "+") == "-",
+        .inverted_button = params.Get("inverted", false) != 0,
         .toggle = params.Get("toggle", false) != 0,
     };
     input_engine->PreSetController(identifier);