Workspace publisher and merger should be services

I suppose we cannot implement a factory completely based on the container.

We could add a method called setSource() to the WorkspacePublisher, in which we might set the needed Workspace to the publisher property.

In the WorkspaceOperationFactory, we should call the new service for WorkspacePublisher like "workspaces.publisher" and then call the method setSource() from itself.

Finally, the new method getPublisher() of WorkspaceOperationFactory should look like:

public function getPublisher(WorkspaceInterface $source) {
    return $this->publisher->setSource($source);
}

Please explain if we could use the DI factory pattern here or review my approach.