* Improved Graph Implementations
Provides new implementation for graph_list.py and graph_matrix.py along with pytest suites for each. Fixes#8709
* Graph implementation style fixes, corrections, and refactored tests
* Helpful docs about graph implementation
* Refactored code to separate files and applied enumerate()
* Renamed files and refactored code to fail fast
* Error handling style fix
* Fixed f-string code quality issue
* Last f-string fix
* Added return types to test functions and more style fixes
* Added more function return types
* Added more function return types pt2
* Fixed error messages
