CID implementation (?)

**Is your feature request related to a problem? Please describe.**

There is a lot of use of the IPFS/multiformats CID spec in NPM. The multiformats package jumps between 1 and 2 million downloads per week. I mainly use the multiformats package for its CID implementation, a spec for addressable, self-describing content IDs that contain info on the text encoding format (e.g. base64), the codec (e.g. cbor), and a hash, to give enough information to decode any binary blob and validate its integrity with the ID.

It is relatively widely used in multiple systems and protocols, including IPFS and AT Protocol.

**Describe the solution you'd like**

I think it's not perfectly clear to me whether CIDs are something that are right for the std library so I'd like to hear people's thoughts and just put it out there as an idea with the acknowledgment that it may be too specific for std lib. Please leave your thoughts!