Fix pathfinding bug

[AttackingOrDefending]

Fix pathfinding bug, where the algo would incorrectly choose the path if the two tiles were on the same axis.

The previous check not new_tile[0] == prev_best[0] (and it's equivalent for vertical movement) would always be true even when moving on the same axis (e.g. if prev_tile is [10, 10], prev_best is [9, 10], and new_tile is [11, 10]).

We now check if the difference is 1, which only happens if it moves on a different axis.

In the example above, if the direction was [1, 1] (top-right) the function would still return False as both if previous_move_direction == self.HORIZONTAL and abs(new_tile[0] - prev_best[0]) == 1: and if prev_tile[1] == new_tile[1]: would be true. Now the first if is correct;y evaluated to false, and the code uses the section that starts at direction = self._get_direction_from_endpoints(end_points) which would previously never be hit.

Also, updates the comments in this function to make it clear what this function does and how it does it.

[AttackingOrDefending]

This bug occured in https://terminal.c1games.com/watchLive/14167288 at round 14 frame 799, where the demolishers decided to go back in the direction they came from instead of forwards, as was the result of the pathfinding code.