Fixes in Bidirectional A* (#2020)

* implement bidirectional astar

* add type hints

* add wikipedia url

* format with black

* changes from review

* fix collision check

* Add testmod()

* # doctest: +NORMALIZE_WHITESPACE

* Codespell: euclidean

* Codespell: coordinates

* Codespell: traversal

* Codespell: remaining

Co-authored-by: John Law <[email protected]>
Co-authored-by: Christian Clauss <[email protected]>