Implement adjacency matrix based graph class

[handlessdude]

Make sure class include:

• [ ] initialization by json import
• [ ] initialization by taking matrix as parameter
• [ ] vertices array getter
• [ ] edges array getter
• [ ] inserting a new vertex to existing graph
• [ ] inserting a new edge to existing graph
• [ ] output to standard output stream (useful for graph mutation debug)
• [ ] output to json file (useful for graph mutation debug)
• [ ] necessary tests
• [ ] necessary docs

[NikitaBogoslovskiy]

take it

[handlessdude]

so json must include a) matrix of Edge class objects b) array of Vertice class objects in order to fetch the appropriate properties