Change scene with PackedScene instead of string

[myin142]

Is your feature request related to a problem? Please describe.
I usually don't like to call the get_tree().change_scene() method because it takes a string. If I ever move or rename the scene I have to find all usages of it and do the same. That's why I always use get_tree().change_scene_to() with a PackedScene. That way it will always be automatically updated whenever I change the path of the scene.

Describe the solution you'd like
Currently only the change_scene() is possible with this plugin. I would be nice if we also have the other option available

[jabsatz]

This is definitely a valid use case. I'll work on it when I have some time, or if you want to implement a solution you're free to open a pull request.

[jabsatz]

To be clear, the solution I have in mind is to make SceneManager.change_scene() take either a String or a PackedScene as a parameter, not to make a whole new method, in order to keep the API as small as possible