### Godot version

4.0.2.stable

### System information

Fedora 37, GeForce RTX 4090 (NVIDIA 530.41.03)

### Issue description

Physical Keycode and Key Label options appear grayed out in the input editor when editing an existing key, even though I should logically be able to change it:

![image](https://github.com/godotengine/godot/assets/180032/54d4c3a5-4da5-4448-b42a-42f0c6870cc2)

If I set the key to another key then change it back, then the **Physical Keycode** and **Key Label** options are no longer grayed out.

cc @bruvzg

### Steps to reproduce

- Open the Project Settings > Input Map tab.
- Create an action, with an associated key. Save it.
- Click the edit button next to the key, and try to change the type without touching the actual key's value.
- Change the key's value back and forth and try to change the type using the dropdown again.

### Minimal reproduction project

N/A
Ref<InputEventKey> k = event;
	Ref<InputEventKey> ko = original_event;
	if (k.is_null() || ko.is_null()) {
		return;
	}
	if (key_mode->get_selected_id() == KEYMODE_KEYCODE) {
		k->set_keycode(ko->get_keycode());
		k->set_physical_keycode(Key::NONE);
		k->set_key_label(Key::NONE);
	} else if (key_mode->get_selected_id() == KEYMODE_PHY_KEYCODE) {
		k->set_keycode(Key::NONE);
		k->set_physical_keycode(ko->get_physical_keycode());
		k->set_key_label(Key::NONE);
	} else if (key_mode->get_selected_id() == KEYMODE_UNICODE) {
		k->set_physical_keycode(Key::NONE);
		k->set_keycode(Key::NONE);
		k->set_key_label(ko->get_key_label());
	}
	_set_event(k, original_event);
}
void InputEventConfigurationDialog::_input_list_item_selected() {