Improve Performance

[AryazE]

https://github.com/AtsushiSakai/PythonRobotics/blob/ad600cd9023e67cd8064b678213d6586d076dd15/PathPlanning/AStar/a_star_searching_from_two_side.py#L80C1-L117C20

In the above function the search for coordinates and neighbors in ob_list and neighbors happens very often, specially for long obstacles.
It would be more efficient to store the obstacles and neighbors in a set as the lookup is done by a hashmap instead of a linear search.

[Mritunjaii]

Hi there! Is this issue still open? I would like to contribute to it. Please assign me this issue under Hacktoberfest2024.
@AtsushiSakai @AryazE