fix: Rollback backward incompatible change

[ajnavarro]

Rollback field name changed here: #74
Also Rollback #84

GraphQL supports slices of one element without adding brackets. Examples:

{
  transactions(filter: {message: [{vm_param: {add_package: {}}}]}) {
    hash
    messages {
      route
      typeUrl
    }
  }
}

{
  transactions(filter: {message: {vm_param: {add_package: {}}}}) {
    hash
    messages {
      route
      typeUrl
    }
  }
}

These two queries are the same.

CC @moul @zivkovicmilos @jinoosss we must avoid breaking backward compatibility in our API.