Breadth First Search [Golang]

#### This issue is about [Breadth First Search](https://github.com/iiitv/algos/tree/master/breadth_first_search).

- [x] Issue Title is in form `Algo/DS Name [Language]`.
- [x] I searched or browsed the repo’s other issues to ensure this is not a duplicate.
- [x] This Algo/DS is worth adding to this repository.
- [x] Assign this issue to me (I want to work on this).
- [ ] I ensure that I am not already assigned to 2 or more issues.
- [x] I will send my PR only after I'm assigned to this issue by any maintainer.
- [x] I understand that I will be unassigned from this issue if I fail to send a PR for this within a week.

Start by inspecting the existing breadth_first_search directory and nearby algorithm implementations in the repository to understand its conventions. Add the missing Golang implementation for Breadth First Search, then verify it matches the repository’s expected structure and behavior; no specific test file is mentioned.

Written by the indexing model from the issue text.