Add TypeField descriptor to ConnObj and Primitive classes

- Replace the layout_obj_type values in classes that derive from ConnObj with TypeField values similar to how the type value is handled in Terminal.py
- Introduce a TypeField for primitive_type in Primitive objects similar to how the type value is handled in Terminal.py
- Note: _type in TypeField needs to be replaced with something like "self._default" and the class needs "def \_\_set_name\_\_(self, name): self.\_default = f"\_{name}"