Set type of all hash to bytes in protobuf files

[NicolasMahe]

Currently the type of all hash are string in the protobuf files and thus on the gRPC API.

We should change it to bytes.

• this allow to generate proto files in with gogoproto with the exact hash type:
  

  engine/protobuf/types/service.proto

  Lines 155 to 159 in 63722e9

  	string hash = 10 [
  	(gogoproto.moretags) = 'validate:"required"',
  	(gogoproto.customtype) = "github.com/mesg-foundation/engine/hash.Hash",
  	(gogoproto.nullable) = false
  	];

• update the mesg-js and/or cli to display the hash in base58
  • the marketplace service is currently using base-x to do it
• we could at the same time, use multihash and multibase to be able to change the hash function and the displayed base in the future