Define supported file extensions for preview (web + mobile)

[IgorShadurin]

Fairdrive is attempting to show previews for file extensions like .html, among others, which unfortunately, the UI currently doesn't support for previewing. This can sometimes cause delays and set up false expectations for the users.

Another approach could be used to clearly define and restrict the file extensions that Fairdrive can successfully preview. By doing this, the application will potentially work faster as it won't waste time trying to preview unsupported file types.

no-preview.mov

[tfius]

i would restrict with supported mime/types, ie. all media files supported by html standard, like images, videos, audio. display text as markdown and json files as either consent or if its not consent as text

[tomicvladan]

This has been implemented in #516