Added Radix Tree in data structures (#6616)

* added radix tree to data structures

* added doctests

* solved flake8

* added type hints

* added description for delete function

* Update data_structures/trie/radix_tree.py

* Update radix_tree.py

* Update radix_tree.py

* Update radix_tree.py

Co-authored-by: Alex de la Cruz <alex@Alexs-MacBook-Air.local>
Co-authored-by: Christian Clauss <cclauss@me.com>