multilingual rule

[pkiraly]

It should check if the content is multilingual (it has at least two items with different language tags).

An example: data:

{
  "id":"Portrait",
  "description":{
    "de":["Portr\u00e4t"],
    "zh":["\u8096\u50cf"]
  }
}

schema:

format: JSON
fields:
 - name: description
   path: $.['description']
   asLanguageTagged: true
   rules:
     - multilingual: true