Shotgun tube toggle hotkey (#4794)

# About the pull request

Adds hotkey to toggling multi magazine on multi tube shotgun.
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# Explain why it's good for the game

Having hotkeys for combat related actions is very important.

</details>


# Changelog
:cl:
add: added shotgun tube toggle hotkey
/:cl:

---------

Co-authored-by: Zonespace <[email protected]>

code/__DEFINES/keybinding.dm

@@ -87,6 +87,7 @@
 #define COMSIG_KB_HUMAN_WEAPON_UNLOAD "keybinding_human_weapon_unload"
 #define COMSIG_KB_HUMAN_WEAPON_ATTACHMENT "keybinding_human_weapon_attachment"
 #define COMSIG_KB_HUMAN_WEAPON_ATTACHMENT_RAIL "keybinding_human_weapon_attachment_rail"
+#define COMSIG_KB_HUMAN_WEAPON_SHOTGUN_TUBE "keybinding_human_weapon_shotgun_tube"
 
 #define COMSIG_KB_HUMAN_WEAPON_TOGGLE_IFF "keybinding_human_weapon_toggle_iff"
 

code/datums/keybinding/human_combat.dm

@@ -190,3 +190,20 @@
 		var/obj/item/weapon/gun/rifle/m46c/COgun = held_item
 		COgun.toggle_iff(human)
 		return TRUE
+
+/datum/keybinding/human/combat/toggle_shotgun_tube
+	hotkey_keys = list("Unbound")
+	classic_keys = list("Unbound")
+	name = "toggle_shotgun_tube"
+	full_name = "Toggle Shotgun Tube"
+	keybind_signal = COMSIG_KB_HUMAN_WEAPON_SHOTGUN_TUBE
+
+/datum/keybinding/human/combat/toggle_shotgun_tube/down(client/user)
+	. = ..()
+	if(.)
+		return
+	var/mob/living/carbon/human/human = user.mob
+	var/obj/item/weapon/gun/shotgun/pump/dual_tube/held_item = human.get_held_item()
+	if(istype(held_item))
+		held_item.toggle_tube()
+		return TRUE