Fixed how NPCs are determined to be in the wilderness for the sake of aggression behavior

What have you done in this MR?

• Changed the behavior of WildernessZone.isInZone to simply loop through the zone's defined borders and check if the entity is within any of them
• Made aggression behavior use WildernessZone.isInZone instead of checking what is effectively Y-level for determining if the NPC is in the wilderness

Fixes a known but not reported bug where various monsters in the slayer tower and hill giants in edgeville dungeon ignore tolerance.

Closes #509 (closed)

Are there any tricky things testers should keep an eye out for?

• No

• Yes, as follows:

• I have tested these changes thoroughly.

• This requires extra testing due to changes to architecture or other similarly risky changes.

• I used the Thanos Tool for any JSON edits where possible, and have attached screenshots of any changes.

• I acknowledge that this contribution will be released under the AGPL license.