Add nested typed collections

[DDAN-17]

Currently, in Godot v4.2.2 if you try to insert the code

var variable : Array[Array[bool]]

into a script, you will get back an error that says "Nested typed collections are not supported." I was wondering if anyone knew enough about the engine to implement this, and if it should be added.

[KerekesDavid]

The same is true for the new typed dictionaries, and not only for nested dicts, but also typed Arrays in Dictionaries are not allowed.

I have multiple use cases where allowing something like this would be very useful:

var pos_dict : Dictionary[Object, Array[Vector2i]]