refactor: support percent-encoded /unix paths

[lidel]

Why

• https://github.com/multiformats/multiaddr/pull/174

is breaking spec change that is incompatible with existing feature in Kubo, where users were able to provide old notation of /unix multiaddrs in both Addresses.API and Addresses.Gateway.

How

This is a PoC that aims to support https://github.com/multiformats/multiaddr/pull/174 while not breaking existing Kubo users.

TODO

• [ ] resolve TODO in daemon.go – decide if we want to move normalization to https://github.com/multiformats/go-multiaddr