Vox Sprite Update (#2668)

## About The Pull Request

Updates a few Vox sprites, mostly backpacks. Adds a proper icon for the
tail hold action.

## Why It's Good For The Game

We love vox in this house

## Changelog

:cl:
imageadd: Added vox sprites & a tailhold icon.
/:cl:

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code/modules/mob/living/carbon/human/species_types/vox.dm

@@ -118,6 +118,7 @@
 /datum/action/innate/tail_hold
 	name = "Tail Hold"
 	desc = "Store an item in your tail's grip."
+	button_icon_state = "tail_hold"
 	var/obj/item/held_item
 	var/mutable_appearance/held_item_overlay