Pick and deploy a filesharing solution to avoid media bloat in the repo

[YuriSizov]

We've got rid of the CMS, but that makes handling of the media files a bit clunky. You have to PR them together with the articles, which is not bad, but that also means that the repo has to keep hundreds of megabyte of images and videos in its history.

We've discussed this a bit with @coppolaemilio and we should probably look into a lightweight solution for filesharing and file hosting, that we can self-host on TuxFamily. It should come with access management, so it can only be used by maintainers, but its role should be simple: drop a file, get a URL back. It would be also nice if we could customize the upload paths so the files are hosted in the download repository on TF, as recommended by TF themselves for static content like that.