A round of sprite improvments/additions. (#6363)

This pr aims to implement a bunch of the work done by Amoryblaine (found in this thread https://forums.aurorastation.org/topic/11698-amorys-sprites/)

    Adds new sprites for the tactical gear available in cargo.
    Adds new, green, sprite for the military belt, the old red one is added as a specific syndicate variant.
    Improves the sprite of the ushanka, adds the old one as a variant by request.
    Adds rolled down sleeves states for two sol uniforms, adds sol tactical helmet and heavy armor vest.
    Adds a TCFL jacket to the loadout.
    Changes the flipped sprites of most caps to be leaning rather than straight.
    Makes the visors of biosuits transparent.
    Recolours the security biosuit from orange to pale blue.
    Recolors the hip holster to be black.
    Makes the tactical gas masks eyes transparent.
    Tweaks the red and blue bandanas to be less bright.
    Adds some missing balaclava sprites, Improves the look of rolled up balaclavas.
    Makes the security berets more fitting with the standard blue one.

code/modules/client/preference_setup/loadout/loadout_head.dm

@@ -4,6 +4,10 @@
 	slot = slot_head
 	sort_category = "Hats and Headwear"
 
+/datum/gear/head/ushanka_grey
+	display_name = "ushanka, grey"
+	path = /obj/item/clothing/head/ushanka/grey
+
 /datum/gear/head/bandana
 	display_name = "bandana selection"
 	path = /obj/item/clothing/head/bandana

code/modules/client/preference_setup/loadout/loadout_suit.dm

@@ -231,6 +231,10 @@
 	coat["military jacket, green"] = /obj/item/clothing/suit/storage/miljacket/green
 	gear_tweaks += new/datum/gear_tweak/path(coat)
 
+/datum/gear/suit/legion_jacket
+	display_name = "Tau Ceti Foreign Legion jacket"
+	path = /obj/item/clothing/suit/storage/legion
+
 /datum/gear/suit/miscellaneous/engi_dep_jacket
 	display_name = "department jacket, engineering"
 	path = /obj/item/clothing/suit/storage/toggle/engi_dep_jacket