Basic Mob Brimdemon (#78424)

## About The Pull Request

Fixes #71330

The brimdemon was basically already perfect (well, it has a novel means
of attacking) so I didn't get too fancy with this one, it's _largely_
just a straightforward conversion.
Following this change it's a little slower to back off, but better at
lining up with people in order to blast them. Additionally, its beam is
now a mob ability so you can give it to other mobs if you so desire.

Because I can't help doing a _little_ tinkering, Brimdemons now explode
2.5 seconds after they die, after a brief warning animation.

## Why It's Good For The Game

Simple mobs must die

## Changelog

🆑
add: Brimdemon corpses release an explosion shortly after death, just to
keep you on your toes.
refactor: Brimdemons now use the basic mob framework which (should)
improve their pathfinding somewhat. Please bug report any unusual
behaviour.
admin: The brimdemon's beam ability can be given to any mob, for your
Binding of Isaac event
/🆑

code/datums/ai/basic_mobs/base_basic_controller.dm

@@ -15,10 +15,13 @@
 
 /datum/ai_controller/basic_controller/able_to_run()
 	. = ..()
-	if(isliving(pawn))
-		var/mob/living/living_pawn = pawn
-		if(IS_DEAD_OR_INCAP(living_pawn))
-			return FALSE
+	if(!isliving(pawn))
+		return
+	var/mob/living/living_pawn = pawn
+	if(!(ai_traits & CAN_ACT_WHILE_DEAD) && IS_DEAD_OR_INCAP(living_pawn))
+		return FALSE
+	if(ai_traits & PAUSE_DURING_DO_AFTER && LAZYLEN(living_pawn.do_afters))
+		return FALSE
 
 /datum/ai_controller/basic_controller/proc/update_speed(mob/living/basic/basic_mob)
 	SIGNAL_HANDLER