External link tiptap extension

[literakl]

List of user supplied Tiptap extensions is in GH issue ueberdosis/tiptap#819

I will need an extension displayed in editor menu that opens a dialog where a user can enter a URL. It will insert new section
with a URL preview:

• twitter, youtube, instagram and facebook will be
• other URLs will be rendered as a box with containing URL's page title (static value is enough)

There must be such component. EditorJS has such plugin. See editor-js/embed#37 (comment). We can recycle their business logic. I think they rely on an external JS library that does the rendering.

The harder part will be an integration into our sources because users can edit their blog and we need to redisplay it in the editor again. Shall we save both TipTap source and generated HTML containing the result? Probably.

I think that the result must contain JS code that is responsible for rendering the link. Backend must not generate HTML on fly for each view request.

Please discuss the proposed solution after an analysis before implementation.

[literakl]

Duplicated by #206