allow downloading data from ipfs://

[TimDaub]

• many contracts return the IANA ipfs:// scheme, but it seems that is not directly supported by IPFS itself: returns false for a valid ipfs url/path! ipfs-shipyard/is-ipfs#48 (comment)
• Infura only allows CIDv1s: https://docs.infura.io/infura/networks/ipfs/how-to/access-ipfs-content
• https://docs.ipfs.io/concepts/content-addressing/#cid-conversion
• That function isIpfs conflates matching URI fragments and checking if the hash is a CID makes it less useful ipfs-shipyard/is-ipfs#52
• Feat/add iana ipfs ipfs-shipyard/is-ipfs#51