TFS lacked any unit tests prior to RBTools 4, and had numerous

type-related issues that broke on Python 3. Users could go back to

Python 2 on earlier versions, but that won't be the case any longer.
This change fixes up all the known type issues. It also adds typing

annotations to all parts of the code, ensuring that we are using the

proper types.
Documentation in parts have been updated as well to help keep things a

bit more maintainable.

Unit tests pass in Python 3.7-3.11.