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/items/crab17.dm

@@ -37,7 +37,8 @@
 	desc = "This is good for spacecoin because"
 	icon = 'icons/obj/money_machine.dmi'
 	icon_state = "bogdanoff"
-	layer = LARGE_MOB_LAYER
+	layer = ABOVE_ALL_MOB_LAYER
+	plane = ABOVE_GAME_PLANE
 	armor = list(MELEE = 80, BULLET = 30, LASER = 30, ENERGY = 60, BOMB = 90, BIO = 0, FIRE = 100, ACID = 80)
 	density = TRUE
 	pixel_z = -8
@@ -203,6 +204,7 @@
 	pixel_z = 300
 	desc = "Get out of the way!"
 	layer = FLY_LAYER//that wasn't flying, that was falling with style!
+	plane = ABOVE_GAME_PLANE
 	icon_state = "missile_blur"
 
 /obj/effect/dumpeet_target

code/game/objects/items/devices/flashlight.dm

@@ -567,7 +567,7 @@
 	light_range = 4
 	light_power = 10
 	alpha = 0
-	layer = 0
+	plane = FLOOR_PLANE
 	on = TRUE
 	anchored = TRUE
 	resistance_flags = INDESTRUCTIBLE | LAVA_PROOF | FIRE_PROOF | UNACIDABLE | ACID_PROOF

code/game/objects/items/devices/forcefieldprojector.dm

@@ -97,6 +97,7 @@
 	icon = 'icons/effects/effects.dmi'
 	icon_state = "forcefield"
 	layer = ABOVE_ALL_MOB_LAYER
+	plane = ABOVE_GAME_PLANE
 	anchored = TRUE
 	pass_flags_self = PASSGLASS
 	density = TRUE

code/game/objects/items/theft_tools.dm

@@ -161,6 +161,7 @@
 	inhand_icon_state = "supermattersliver"
 	pulseicon = "supermatter_sliver_pulse"
 	layer = ABOVE_MOB_LAYER
+	plane = GAME_PLANE_UPPER
 
 
 /obj/item/nuke_core/supermatter_sliver/attack_tk(mob/user) // no TK dusting memes

code/game/objects/items/weaponry.dm

@@ -127,7 +127,7 @@ for further reading, please see: https://github.com/tgstation/tgstation/pull/301
 /obj/item/claymore/highlander/process()
 	if(ishuman(loc))
 		var/mob/living/carbon/human/H = loc
-		loc.layer = LARGE_MOB_LAYER //NO HIDING BEHIND PLANTS FOR YOU, DICKWEED (HA GET IT, BECAUSE WEEDS ARE PLANTS)
+		loc.plane = GAME_PLANE_UPPER_FOV_HIDDEN //NO HIDING BEHIND PLANTS FOR YOU, DICKWEED (HA GET IT, BECAUSE WEEDS ARE PLANTS)
 		ADD_TRAIT(H, TRAIT_NOBLEED, HIGHLANDER_TRAIT) //AND WE WON'T BLEED OUT LIKE COWARDS
 	else
 		if(!(flags_1 & ADMIN_SPAWNED_1))
@@ -242,7 +242,7 @@ for further reading, please see: https://github.com/tgstation/tgstation/pull/301
 		return INITIALIZE_HINT_QDEL
 
 /obj/item/claymore/highlander/robot/process()
-	loc.layer = LARGE_MOB_LAYER
+	loc.plane = GAME_PLANE_UPPER_FOV_HIDDEN
 
 /obj/item/katana
 	name = "katana"
@@ -936,6 +936,7 @@ for further reading, please see: https://github.com/tgstation/tgstation/pull/301
 	icon_state = "highfreq_slash"
 	alpha = 150
 	duration = 0.5 SECONDS
+	layer = ABOVE_ALL_MOB_LAYER
 	plane = ABOVE_GAME_PLANE
 
 /obj/effect/temp_visual/slash/Initialize(mapload, atom/target, x_slashed, y_slashed)