Include prefix in Multihash.toString()

[vorburger]

ToDo:

• Test coverage

[odisseus]

The premise of this PR is completely wrong.

First, Qm isn't the right prefix for Base58. In fact, no valid Multibase string can start with Q. See specification, implementation.

The hashes that start with Qm are typical (though not required) for IPFS, and they actually don't include the Multibase prefix. See discussion.

Second, the method Base58.encode from io.ipfs.multibase produces results which already include the base prefix. See test examples.

[vorburger]

@odisseus sorry for a (very) delayed response, but better late than never?

Yeah, I meanwhile that I better understand what's what agree that this as-is doesn't make any sense.

Somewhat related: The underlying problem that I really was after was to "have an object that encapsulates both a Multihash and the Multibase that it was originally expressed in (e.g. to provide it as context in error messages)". In my project, I have now written a MultihashWithMultibase for this purpose. Do you think adding that here could make sense? If yes, I'm happy to raise a PR. If no, I'll close this issue.

@ianopolous @mk868 any thoughts?