Update auras when a formation member renames

Reported on forum: https://wildfiregames.com/forum/index.php?/topic/25196-when-unit-levels-up-he-loses-armor-bonus-from-athens-hero/

Relevant diff: https://code.wildfiregames.com/D997

Differential Revision: https://code.wildfiregames.com/D1727
Patch by: @Freagarach