Refactor visibility receive and real-time processing infrastructure

Our understanding of the scientific and technical requirements of the receive and real-time processing pipelines has evolved over time. In testing, it has emerged that we need to run multiple receive processes on a single node for Low at AA0.5. Furthermore the data needs to pass through multiple stages of processing downstream of receive, which is not easily supported in the current implementation. Therefore the software infrastructure used to implement the pipelines needs to be refactored to better support these things.

• The infrastructure underlying the receive and real-time processing has been refactored to support multiple receivers and the chaining together of pipeline steps (e.g. receive ➔ pre-processing ➔ gain calibration)
• The visibility receive processing script has been updated to deploy processing components using the new version of the infrastructure.