New powernet light flicker (#92567)

## About The Pull Request

Changes light flicker to be an overlay instead of a rapid turning on/off
of the light itself. It acts similar to a brownout and delayed restart
of the light.

The introduction of lights flickering when the powernet is hit by a bomb
is a cool effect, but makes it very apparent the current flicker
method's limitations. Rapid cycling of machinery on/off as fast as 0.5
seconds, spanning over dozens of lights at a time leads to the subsystem
not being able to keep up with the lighting changes. It ultimately
results in just a single broken looking change of lighting

<details>
<summary>Screenshots/Videos</summary>
Before:


https://github.com/user-attachments/assets/8237e72e-1edc-4423-b48b-8dd403ee3111


https://github.com/user-attachments/assets/f3a3d481-61fa-4fd9-b51c-3c1e080e129c

After:


https://github.com/user-attachments/assets/0fa2bbfd-4ca7-422a-8cd1-b6b738addb0f


https://github.com/user-attachments/assets/8b8b10b9-912a-4476-9a11-985f79228500

</details>

## Why It's Good For The Game

The powernet flicker effect looks better (and also now has an electrical
sizzle sound)

## Changelog

🆑 LT3
code: Improved powernet light flickering
/🆑

code/modules/mob/living/basic/space_fauna/revenant/revenant_abilities.dm

@@ -192,7 +192,7 @@
 		if(window.fulltile)
 			new /obj/effect/temp_visual/revenant/cracks(window.loc)
 	for(var/obj/machinery/light/light in victim)
-		light.flicker(20) //spooky
+		light.flicker(rand(3, 5)) //spooky
 
 //Malfunction: Makes bad stuff happen to robots and machines.
 /datum/action/cooldown/spell/aoe/revenant/malfunction