Added Skin Reagent Trait (#19083)

* Added Skin Reagent Trait

On today's episode of "Satin sees a funny suggestion on the discord and implements it, but it's harder than she expects":

Added a new Skin Reagent trait, that allows you to pick one of six reagents that coat your skin and are applied to people when they lick you. These include: Ethanol, Capsaicin, Sleep Toxin, Rainbow Toxin, Paralysis Toxin and Pain Enzyme.

Does not trigger on licking yourself.

Also added a new option to traits to allow you to use a single list for them to select preferences, using a list variable called "multiple_choice".

Tested and seems to work great.

* Have salt as an option too, go on

* Removes flags, lazys the list

Not 100% sure if I've done the lazy right, I've not done much with lazy lists before.

code/modules/vore/eating/living_vr.dm

@@ -24,6 +24,7 @@
 	var/digestion_in_progress = FALSE	// Gradual corpse gurgles
 	var/trash_catching = FALSE					//Toggle for trash throw vore
 	var/list/trait_injection_reagents = list()	//List of all the reagents allowed to be used for injection via venom bite
+	var/skin_reagent
 	var/trait_injection_selected = null			//What trait reagent you're injecting.
 	var/trait_injection_amount = 5				//How much you're injecting with traits.
 	var/trait_injection_verb = "bite"			//Which fluffy manner you're doing the injecting.
@@ -458,6 +459,10 @@
 		if((tasted.touch_reaction_flags & SPECIES_TRAIT_PERSONAL_BUBBLE) && (!tasted.grabbed_by.len || !tasted.stat))
 			visible_message(span_warning("[src] tries to lick [tasted], but they dodge out of the way!"),span_warning("You try to lick [tasted], but they deftly avoid your attempt."))
 			return
+		if(tasted.skin_reagent && ishuman(src) && (tasted != src))
+			var/mob/living/carbon/human/us_but_human = src
+			us_but_human.ingested.add_reagent(tasted.skin_reagent, 10)
+
 		visible_message(span_vwarning("[src] licks [tasted]!"),span_notice("You lick [tasted]. They taste rather like [tasted.get_taste_message()]."),span_infoplain(span_bold("Slurp!")))
 		//balloon_alert_visible("licks [tasted]!", "tastes like [tasted.get_taste_message()]")
 	// This has already passed consent tests