Multiaddr URI scheme

[MarcoPolo]

I'd like to propose the following URI scheme for multiaddrs: multiaddr:<string-encoded-multiaddr>.

This would give us the ability to pass in a multiaddr where a URI is expected (e.g. HTTP redirects). A bit more context here: libp2p/specs#568.

I don't think any multiaddrs in use today are incompatible with the generic URI syntax. Specifically section 3.3 for Paths.

[MarcoPolo]

For multiaddr components that use multibase, the generator of the URI string should ensure the multibase used is valid as a path segment.