[Feature] Add get_word_path function to word_search.py

[maknelso]

Feature description

I would like to add a new function, lets called get_word_path to backtracking/word_search.py.

Existing exits_word function is great for bool checks but users may want to know the specific coordinates for highlighting or path finding.

The new function will:

1. Returns a list[tuple[int,int]] | None instead of bool
2. Use a dedicated backtracking approach to capture the coordinates.
3. Include modern type hints and comprehensive doctests.

I have tested implementation ready. May I submit a PR?