Find all missed locales which are not in JSON file

[vladstarikov88]

Is your feature related to a specific framework or general for this extension
No

Is your feature request related to a problem? Please describe.
I can' detect all missed locales I used in project

Describe the solution you'd like
Full list of missed locales which doesn't exists inside the JSON file

Additional context
For example JSON file has only 1 string

{
  "common": "hello"
}

But in my project there is a file which used common.world string.

I want to see the full list of missed locales which are no in the JSON file

[vladstarikov88]

May be such functionallity is implemented already, but I can' find it. I wonder if somebody help me

[vladstarikov88]

I already prepared my own solution to get all such missed locales inside the project. It response an array of missed locales.

I can create PR if this functionallity needed