Refactor areCausallyRelatedUsingBFS to Use BFS Correctly and Remove Duplicated Code

[trungnotchung]

The areCausallyRelatedUsingBFS function incorrectly uses DFS instead of BFS by employing a stack.

Additionally, it duplicates traversal logic when checking for causality in both directions (hash1 -> hash2 and hash2 -> hash1). This function should be refactored to use a queue for BFS and to separate the traversal logic into a reusable helper function to improve readability and maintainability.

File: packages/object/src/hashgraph/index.ts