Gun safeties work in more slots (#3342)

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## About The Pull Request

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#3341 
Gun safeties can be toggled in 1st level storage slot (e.g hands, suit
slots, belts, pockets, back) instead of just the hands. Guns in
containers (e.g. backpacks) aren't togglable.

## Why It's Good For The Game

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Seems like a nice QOL thing to have.

## Changelog

:cl:
add: Gun safeties can be toggled from 1st level storage slots.
/:cl:

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code/modules/projectiles/gun.dm

@@ -689,8 +689,8 @@
 	. = ..()
 	if(!has_safety)
 		return
-
-	if(src != user.get_active_held_item())
+	// only checks for first level storage e.g pockets, hands, suit storage, belts, nothing in containers
+	if(!in_contents_of(user))
 		return
 
 	if(isliving(user) && in_range(src, user))