Core: NPC Interaction change for unfriendly reputation.

For units with unfriendly reputation, check using the normal reaction function, instead of reading faction directly.

This allows specific buffs that alter creature reaction to work on the player, this allowing players to complete quests.

Closes #13629

(cherry picked from commit 17f6dcb76282523ac43d8a1e6cebbe0043ab44fa)

Conflicts:
	src/server/game/Entities/Player/Player.cpp