Vertex pathfinder - fixes to quadrant optimisation to ensure units don't take detours around obstructions.
Compute the outward quadrants once and for all instead of setting them dynamically, because there is no reason why we should always arrive from the same quadrant as the first time we see a vertex.
Don't consider quadrants for the start-vertex, because of the edge expansion (which can put us in illegal quadrants)

These result in (much) better paths, the tradeoff being that we now look at some more vertices.

Fixes #5476

Differential Revision: https://code.wildfiregames.com/D1908