makes the alt naga tail (dual colour) go behind clothing instead of o…

…ver it (Citadel-Station-13#6783)

## About The Pull Request
title
does this by just splitting the one sprite into a front and behind, so
the 'behind' sprite won't go above clothing, but the 'front' sprite will

## Why It's Good For The Game
why is the bottom of my sweater getting eaten by the tail

## Changelog

:cl:
tweak: makes the alt naga tail (dual colour) go behind clothing instead
of over it
/:cl:

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code/modules/sprite_accessories/tail/taurs.dm

@@ -155,8 +155,9 @@
 /datum/sprite_accessory/tail/legacy_taur/naga/naga_2c_alt
 	name = "Naga dual-color alt (Taur)"
 	id = "tail_taur_naga_colorable_alt"
-	icon_state = "altnaga_s"
+	icon_state = "altnaga"
 	extra_overlay = "altnaga_markings"
+	icon_sidedness = SPRITE_ACCESSORY_SIDEDNESS_FRONT_BEHIND
 
 /datum/sprite_accessory/tail/legacy_taur/naga/naga_tailmaw
 	name = "Naga Tailmaw (Taur)"