Add rich text component

[Syndesi]

The rich text component should be used for Markdown files and other text formats from Microsoft Office, Libre Office etc., and should be able to a) display a thumbnail, b) display the rich text (ideally as HTML, although rendered as an image would work as well) and c) allow to copy both the rich text as well as the raw text content.

Todos

• Can browsers render thumbnails of all required file types efficiently? If not, does this component require a bot integration to render thumbnails server side?