core/hid: Improve accuracy of the keyboard implementation

src/input_common/main.h

@@ -134,6 +134,9 @@ private:
 /// Generates a serialized param package for creating a keyboard button device.
 std::string GenerateKeyboardParam(int key_code);
 
+/// Generates a serialized param package for creating a moddifier keyboard button device.
+std::string GenerateModdifierKeyboardParam(int key_code);
+
 /// Generates a serialized param package for creating an analog device taking input from keyboard.
 std::string GenerateAnalogParamFromKeys(int key_up, int key_down, int key_left, int key_right,
                                         int key_modifier, float modifier_scale);