Added basic folder functionalities for the python-tss-sdk

[SimHeb]

Added the following functions

1. get_folder --> gets a folder by ID, can get_all_children=True if needed
2. get_folder_by_path --> gets a folder by a given folder_path, can get_all_children=True if needed
3. lookup_folders and get_folder_json are helper functions created for the get_secret_json respectively.
4. get_child_folder_ids_by_folderid --> gets a list of child folder IDs from a given folder IDs. limitToDirectDescendents is set to true to only get the actual child folders, to prevent bigger JSON loads.
5. Added a SecretFolder DataClass which represents a folder struct in python

All functions have been tested with pytest. We have an internal SecretServer instance, so it was not possible for me to test on a secretservercloud instance.