Make descriptions for item variants optional.

[Uwuewsky]

Is your feature request related to a problem? Please describe.

Right now the description for the gun variant is mandatory, not having it will cause a loading error. As an example:

Cataclysm-DDA/data/json/items/gun/9mm.json

Lines 246 to 260 in 2000b9f

	{
	"id": "briefcase_smg",
	"copy-from": "hk_mp5k",
	"looks_like": "hk_briefcase",
	"type": "GUN",
	"name": { "str": "MP5 operational briefcase" },
	"description": "A hard-sided briefcase with a trigger in the handle and a concealed hole in the side. To fire the internally mounted MP5K-PDW, one braces the briefcase at the waist, ensures the hole is pointed at the enemy, and squeezes the trigger. Precision and handling are severely hampered by the shape of the briefcase, but if you need to 'hand over the goods' or look low profile while bodyguarding, this is your gun. When the briefcase is open, the MP5 may be reloaded or dismounted.",
	"variant_type": "gun",
	"variants": [
	{
	"id": "briefcase_smg",
	"name": { "str": "H&K operational briefcase" },
	"description": "A hard-sided briefcase with a trigger in the handle and a concealed hole in the side. To fire the internally mounted MP5K-PDW, one braces the briefcase at the waist, ensures the hole is pointed at the enemy, and squeezes the trigger. Precision and handling are severely hampered by the shape of the briefcase, but if you need to 'hand over the goods' or look low profile while bodyguarding, this is your gun. When the briefcase is open, the MP5 may be reloaded or dismounted."
	}
	],

I'm making a patch so that almost every weapon has a generic and specific brand name, and I don't want to write descriptions for them yet. So far I have automatically copied the descriptions into the variants, but it would be better if it could be omitted entirely so as not to bloat the files.

Solution you would like.

 "name": { "str": "MP5 operational briefcase" }, 
 "description": "A hard-sided briefcase with a trigger in the handle and a concealed hole in the side.  To fire the internally mounted MP5K-PDW, one braces the briefcase at the waist, ensures the hole is pointed at the enemy, and squeezes the trigger.  Precision and handling are severely hampered by the shape of the briefcase, but if you need to 'hand over the goods' or look low profile while bodyguarding, this is your gun.  When the briefcase is open, the MP5 may be reloaded or dismounted.", 
 "variant_type": "gun", 
 "variants": [ 
   { 
     "id": "briefcase_smg", 
     "name": { "str": "H&K operational briefcase" }
   } 
 ], 

Describe alternatives you have considered.

Also make the ID field optional if there is only one variant? By default it could be the same as the parent.

Additional context

No response

[ZhilkinSerg]

What's the point to have a variant w/o a distinct description?