Implement Edmonds-Karp Algorithm

[AhmedHamdiy]

Description:
The Edmonds-Karp algorithm is a specific implementation of the Ford-Fulkerson method that finds the maximum flow in a flow network. It uses Breadth-First Search (BFS) to find the shortest augmenting path, ensuring a time complexity of O(VE²).

Why is this needed?
This algorithm is widely used in network flow problems, such as:

• Network routing
• Bipartite matching
• Circulation problems

Tasks:

• Implement the Edmonds-Karp algorithm class using BFS for augmenting path selection.
• Ensure the function accepts a directed, weighted graph with edge capacities.
• Return the maximum flow value and the corresponding flow in the network.
• Write unit tests to verify correctness.

[AhmedHamdiy]

@Ducasse Can I work on this issue. I think it's a good feature to be added to pharo