The clearance between two zones could be rather slow. This was in part
to trying to do triangle-triangle collisions between zones when we only
need outline collision and in part to the shape_line_chain collision
routine. The shape_line_chain collisions don't need to recreate
segments on each iteration and should instead create them once and using
this to check all collisions
Fixes https://gitlab.com/kicad/code/kicad/-/issues/17327
3cc1617f5a