Greedy min vertex cover hacktoberfest (#5241)

* added complete graph generator function

* added doctest, type hints, wikipedia explanation

* added return type hint for function complete_graph

* added descriptive name for the parameter: n

* random graph generator with doctest and type hints

* added Greedy min vertex algorithm

* pre-commit hook(s) made changes

* Delete complete_graph_generator.py

* Delete random_graph_generator.py

* fixed doctest

* updated commit following highligths

* fixed following pre-commit highlights

* modified variables names