Refactor floodlights

- Fixes #9543
- Removes ugly floodlight/proc/updateicon() and replaces it with proper floodlight/update_icon() which is standard on all objects/items. Does the same refactor for power cells and adjusts the proc call in relevant files (hence the amount of 1-line changes in various files)
- Makes floodlights properly use CELLRATE. Their load is 200 watts. Cell adjusted accordingly, it starts with 1k cell, which is enough for ~40 minutes (roughly)
- Floodlights with almost discharged cell (less than 10%) ocassionally "flicker", dimming for few seconds. This serves as indicator that the power cell is running low.
- Floodlight luminosity adjusted. They now shine slightly more, espicially closer to the floodlight.

code/modules/mob/living/silicon/robot/drone/drone_items.dm

@@ -194,7 +194,7 @@
 				wrapped = A.cell
 
 				A.cell.add_fingerprint(user)
-				A.cell.updateicon()
+				A.cell.update_icon()
 				A.cell.loc = src
 				A.cell = null
 
@@ -211,7 +211,7 @@
 				wrapped = A.cell
 
 				A.cell.add_fingerprint(user)
-				A.cell.updateicon()
+				A.cell.update_icon()
 				A.updateicon()
 				A.cell.loc = src
 				A.cell = null

code/modules/mob/living/silicon/robot/robot.dm

@@ -746,7 +746,7 @@
 	if(opened && !wiresexposed && (!istype(user, /mob/living/silicon)))
 		var/datum/robot_component/cell_component = components["power cell"]
 		if(cell)
-			cell.updateicon()
+			cell.update_icon()
 			cell.add_fingerprint(user)
 			user.put_in_active_hand(cell)
 			user << "You remove \the [cell]."