Prevent Pathfinding out of World Border

This prevents Entities from trying to run outside of the World Border

TODO: This doesn't prevent the pathfinder from using blocks outside the world border as nodes. We can fix this
by adding code to all overrides in:
    NodeEvaluator:
    public abstract BlockPathTypes getBlockPathType(BlockGetter world, int x, int y, int z);

to return BLOCKED if it is outside the world border.

paper-server/patches/sources/net/minecraft/world/entity/ai/navigation/PathNavigation.java.patch

@@ -50,7 +50,7 @@
 +            // Paper start - EntityPathfindEvent
 +            boolean copiedSet = false;
 +            for (BlockPos possibleTarget : positions) {
-+                if (!new com.destroystokyo.paper.event.entity.EntityPathfindEvent(this.mob.getBukkitEntity(),
++                if (!this.mob.getCommandSenderWorld().getWorldBorder().isWithinBounds(possibleTarget) || !new com.destroystokyo.paper.event.entity.EntityPathfindEvent(this.mob.getBukkitEntity(), // Paper - don't path out of world border
 +                    io.papermc.paper.util.MCUtil.toLocation(this.mob.level(), possibleTarget), target == null ? null : target.getBukkitEntity()).callEvent()) {
 +                    if (!copiedSet) {
 +                        copiedSet = true;