Make it easier to set-up the required amount of retrievers

[Dominik Durner]

• Use default throughput per core values, that can be adapted by the user
• Use default requests per retriever values, that can be adapted by the user
• Use the network throughput information from the instance to calculate concurrency and outstanding requests
• Build pipeline to automatically get the information for the cloud vendors instances
• Integrate that into a config helper class that can be used easily, e.g.,
  - config.requiredThreadCount() to give the user the number of retriever threads that need to started
  - New constructor TaskSendReceiverGroup(config) to initialize the values more easily