Firewall/lightning wall not dealing damage at every other tile

[neube3]

Related to https://github.com/diasurgical/devilutionX/issues/6189

See the above issue first for a starting point, otherwise you might be a bit lost here.

This issue is about complementary fix - not for the flamewave, but for fire- and lightning wall.

Vanilla is broken and it's completely safe to go through diagonally on tiles between actual fire/lightning wall tiles (i.e. yellow arrow is safe if yellow squares were a firewall). We want that fixed.

AJenbo proposed dealing damage to actors trying to cross the wall. Standing on 4,1 is fine, but moving across the yellow tiles should damage you until you are fully on the 3,0 tile.

So - crossing the red zones added on the image below should be dealing damage to an actor.