Publish IPNS names using a signature instead of private key

To use `/api/v0/name/publish` I need to import private key to node first. For scenarios like in https://github.com/ipfs-shipyard/js-did-ipid I will prefer to keep my private key in wallet and sent to HTTP API an signature as proof of ownership of this key. So the IPFS node will not have access to private key but will be able to publish IPNS names still.