Improved raid mob spawns/pathfinding

Hostile mobs shouldn't be able to spawn within a certain radius of any mob they can attack. This is usually the case, but during raids, pillagers can spawn right next to you or near villagers. When they don't, however, they are likely to fall deep into caves, especially on rough terrain or Amplified Worlds. This could be fixed by all illagers in the raid first pathfinding a clear path to the village targeted (the blocks required for the place to have a raid) while the boss bar for the raid fills up. Then all of the illagers could follow that path once they spawn, instead of any random pathfinding into caves.

This would improve the raid experience because raids have a time limit, and having to search through caves usually takes longer than that, so you can't get Totems of Undying or Hero of the Village.