Upgrades GODMODE from a flag to a trait. (#86596)

## About The Pull Request
GODMODE has a lot of sources that toggle it. From admin-stuff to status
effects, components, actions and mobs which are supposed to be
invincible. It's better off as a trait than a flag, so we can manage
these sources.

## Why It's Good For The Game
See above.

## Changelog

🆑
admin: godmode is now a datum trait instead of a bitflag. This means the
process for toggling it is a little different now.
/🆑

code/modules/mob/living/basic/basic_defense.dm

@@ -159,7 +159,7 @@
 	..()
 
 /mob/living/basic/update_stat()
-	if(status_flags & GODMODE)
+	if(HAS_TRAIT(src, TRAIT_GODMODE))
 		return
 	if(stat != DEAD)
 		if(health <= 0)