Adds Ray Workflow: Multiple Run Support, Distributed Hyperparameter Tuning, and Consistent Setup Across Local/Cloud (#1301)

This PR adds Ray support, which enables a lot of really cool stuff by
leveraging the existing Hydra support, including but not limited to:

- Several training runs at once in parallel or consecutively with
minimal interaction
- Using the same training setup everywhere (on cloud and local) with
minimal overhead
- Tuning hyperparameters
- Tuning hyperparameters in parallel on multiple GPUs and/or multiple
GPU Nodes
- Simultaneously tuning model hyperparameters for different
environments/agents
- Resource Isolation