feat: improved CID column (filename and dnslink support)

[lidel]

This PR closes #42 by taking advantage of DNSLink flag added in https://github.com/ipfs/go-ipfs/pull/7699

Changes:

• [x] Links to direct CIDs now have ?filename= param to preserve name and content type
• [x] When page is loaded on DNSLink website then there is no public gateway endpoint mounted.
  • We still want to keep CID column, so as a replacement, clicking on a CID opens http://cid.ipfs.io#<cid>
• [x] figured out why CI adds -e to <style> block, npm run build should now produce same output on all unix platforms
• [x] did end-to-end test with https://github.com/ipfs/go-ipfs/pull/7699 and things work as expected

[lidel]

@jessicaschilling I don't expect more changes here, so this is ready to be reviewed (and if looks good, to be released). Then we can switch https://github.com/ipfs/go-ipfs/pull/7699 to release version :)