GDExtension expose add_move_array_element_function

[nonameentername]

Add function to editor plugin to allow use in GDExtension

[AThousandShips]

I don't think this requires a dedicated PR here, the file is updated when changes occur by maintainers

[dsnopek]

Thanks!

However, @AThousandShips is correct - we don't normally commit piecemeal changes to extension_api.json, instead we sync periodically with Godot (and developers can easily generate their own files in the meantime). So, if/when the Godot change is merged, it'll work it's way here in a future sync