Refactor Signature Message Construction

[bogdanfazakas]

the message used for signature validation is constructed by concatenating consumerAddress, datasets[0].documentId, and nonce.
we have use cases when documentId is undefined and that is ok.

create a new signature structure

message = 'consumerAddress'+'nonce'+'cmd'
the signature flow stays the same we only update the message structure!

breaking change: Node, ocean.js, ocean-orchestrator, ocean-cli(just check) , motoring, dashboard