New Algorithm (BFS)

Hello!

I would like to add the search algorithm Breadth-first search (BFS), is an algorithm for traversing or searching tree or graph.

Reference: https://en.wikipedia.org/wiki/Breadth-first_search

No file or test entry point is named. First inspect the repository's existing graph-algorithm organization and conventions, then use the linked Breadth-first search reference to define the expected traversal behavior. Done means BFS is added in the project's established style and its behavior is covered by the repository's relevant checks, if available.

Written by the indexing model from the issue text.