Integrate ability to pick a single response when multiple RAG/LLMs are configured

[garvk]

1. We need a process that allows for a single answer to be chosen even when multiple RAGs/LLMs are configured in an iteration. This will be helpful to be used in the final application where aggrag is being used as the orchestration library

2. After 1, we will need to have the process be extended to pick one or 'fewer' RAGs/LLMs than what are configured in the iteration. This will require end user evaluation feedback loop as that will drive the 'runtime' or 'dynamic' improvement in the iteration configuration.