Add stats to group response

[noctera]

We have get routes for language packages and groups GET: /api/languagePackage GET: /api/languagePackage/{languagePackageId}/group which return information about all the existing language packages and groups.

While the language package route as an optional stats parameter that allows adding stats about the existing vocabs

"stats": {
      "vocabularies": {
        "all": 0,
        "active": 0,
        "inactive": 0,
        "unresolved": 0,
        "unactivated": 0,
        "learnedToday": {
          "dueToday": 0,
          "correct": 0,
          "wrong": 0
        }
      }
    }

the group route does not have such. In order to show stats in the group tag of the library, we have to add

1. stats in the group route

2. and to the included groups in the language package route.

[tintinthong]

Hello, I would like to take on this issue for hacktoberfest. Is that ok??

[noctera]

Yes, I will assign you