Add breadth-first search algorithm example

[kevinjycui]

Implementing a breadth-first search (BFS) or 廣度優先搜索 example
Calculates the shortest distance between two nodes on a cyclic bidirectional graph.
I'm not very good at the syntax so the format may need some fixing. Otherwise, it works.

[antfu]

Comments with prefix 批曰。 would be better.
And for the failing test, could you help run npm run test:update and commit the snapshot?

Besides that, it looks good to me. Thanks for the new example!

[kevinjycui]

I used the prefix 注曰。 instead since I felt that it fit better. Hope that's okay!

[LingDong-]

Awesome, thanks a lot for the new example!