Return execution result from command dispatch

[JoanZapata]

Router.dispatch/1 doesn't allow to retrieve the events produced by the aggregate in response to the command.

It could either be added as a breaking change to unify the API:

# Would have previously returned :ok
iex> Router.dispatch(command)
{
  :ok, 
  %ExecutionResult{
    aggregate_uuid: aggregate_uuid, 
    aggregate_version: aggregate_version, 
    events: events,
    metadata: metadata,
  }
}

Or as a non-breaking change, using a new option

iex> Router.dispatch(command)
:ok

iex> Router.dispatch(command, include_aggregate_version: true)
{:ok, aggregate_version}

iex> Router.dispatch(command, include_execution_result: true)
{
  :ok, 
  %ExecutionResult{
    aggregate_uuid: aggregate_uuid, 
    aggregate_version: aggregate_version, 
    events: events,
    metadata: metadata,
  }
}

[JoanZapata]

@slashdotdash If that's ok, I'll make a naive implementation of the second option and submit a pull request.

[slashdotdash]

Yes, I think extending the API with the non-breaking change is preferable for now. Good luck.