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

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

code/game/objects/effects/effect_system/effects_explosion.dm

@@ -33,6 +33,7 @@
 	icon_state = "explosion"
 	opacity = TRUE
 	anchored = TRUE
+	layer = ABOVE_ALL_MOB_LAYER
 	plane = ABOVE_GAME_PLANE
 	mouse_opacity = MOUSE_OPACITY_TRANSPARENT
 	pixel_x = -32

code/game/objects/effects/effect_system/effects_foam.dm

@@ -12,7 +12,7 @@
 	anchored = TRUE
 	density = FALSE
 	layer = EDGED_TURF_LAYER
-	plane = ABOVE_GAME_PLANE
+	plane = GAME_PLANE_UPPER
 	mouse_opacity = MOUSE_OPACITY_TRANSPARENT
 	var/amount = 3
 	animate_movement = NO_STEPS
@@ -271,6 +271,7 @@
 	opacity = TRUE // changed in New()
 	anchored = TRUE
 	layer = EDGED_TURF_LAYER
+	plane = GAME_PLANE_UPPER
 	resistance_flags = FIRE_PROOF | ACID_PROOF
 	name = "foamed metal"
 	desc = "A lightweight foamed metal wall that can be used as base to construct a wall."