Wrong metadata json for links

[mdrlzy]

code:LINK field is missing in kind json file for links

[mdrlzy]

code changed to kind

[kirillt]

Also, this JSON in cache/metadata is incorrect:

{
  "title": "Яндекс",
  "description": "Найдётся всё",
  "url": "https://ya.ru",
  "image": "https://yastatic.net/s3/home-static/_/43/43e341fd2770891523066b0f25051a7b.png",
  "object_type": "website",
  "locale": "ru_RU"
}

• We may keep automatic title in metadata, but we should use it somehow (as a secondary title in addition to what the user specified? as a default value?)
• Same with description
• We must not store url in metadata, that's what the resource contains
• Are image, object_type and locale fields really useful?

[kirillt]

Complete this first:

• Metadata extraction pipeline #58