Incorrect handling of IPFS links

The renderer should handle IPFS links and add the prefix if the ipfsPrefix option is provided. Looks like there's an initial implementation that should handle legacy /ipfs/ or //ipfs/ links but the modern protocol ipfs:// is missing. There's also a bug in current implementation that makes it possible to use single format only. Renderer should support all three formats.

On the occasion, we should make ipfsPrefix option optional.