Fixes layering issues brought by the FoV PR. (#63903)

* Fixed most (not all) incorrect planes and layers detected by the unit test.

code/modules/power/gravitygenerator.dm

@@ -173,6 +173,7 @@ GLOBAL_LIST_EMPTY(gravity_generators) // We will keep track of this by adding ne
 		if(count <= 3) // Their sprite is the top part of the generator
 			part.set_density(FALSE)
 			part.layer = WALL_OBJ_LAYER
+			part.plane = GAME_PLANE_UPPER
 		part.sprite_number = count
 		part.main_part = src
 		parts += part

code/modules/power/lighting/light.dm

@@ -5,6 +5,7 @@
 	icon_state = "tube"
 	desc = "A lighting fixture."
 	layer = WALL_OBJ_LAYER
+	plane = GAME_PLANE_UPPER
 	max_integrity = 100
 	use_power = ACTIVE_POWER_USE
 	idle_power_usage = 2

code/modules/power/lighting/light_construct.dm

@@ -5,6 +5,7 @@
 	icon_state = "tube-construct-stage1"
 	anchored = TRUE
 	layer = WALL_OBJ_LAYER
+	plane = GAME_PLANE_UPPER
 	max_integrity = 200
 	armor = list(MELEE = 50, BULLET = 10, LASER = 10, ENERGY = 0, BOMB = 0, BIO = 0, FIRE = 80, ACID = 50)
 

code/modules/power/solar.dm

@@ -35,6 +35,7 @@
 	panel.icon = icon
 	panel.icon_state = "solar_panel"
 	panel.layer = FLY_LAYER
+	panel.plane = ABOVE_GAME_PLANE
 	Make(S)
 	connect_to_network()
 	RegisterSignal(SSsun, COMSIG_SUN_MOVED, .proc/queue_update_solar_exposure)

code/modules/power/supermatter/supermatter.dm

@@ -1179,6 +1179,7 @@ GLOBAL_DATUM(main_supermatter_engine, /obj/machinery/power/supermatter_crystal)
 	gasefficency = 0.125
 	explosion_power = 12
 	layer = ABOVE_MOB_LAYER
+	plane = GAME_PLANE_UPPER
 	moveable = TRUE
 	psyOverlay = /obj/overlay/psy/shard