Returns if the given NPC class name is a friend.

Returns true if the entity name is one of the following:

• "npc_alyx"
• "npc_barney"
• "npc_citizen"
• "npc_dog"
• "npc_eli"
• "npc_fisherman"
• "npc_gman"
• "npc_kleiner"
• "npc_magnusson"
• "npc_monk"
• "npc_mossman"
• "npc_odessa"
• "npc_vortigaunt"