Updated the OpenSourceSwarm for use with astra-assistants

This [new setup](https://github.com/phact/agency-swarm-lab/blob/astra-assistants/AstraOpenSourceSwarm/README.md) for [astra-assistants](https://github.com/datastax/astra-assistants-api) is only 3 steps (no docker) and 4 steps (with docker) if ollama is required. This is much simpler than the [previous setup](https://github.com/VRSEN/agency-swarm-lab/tree/main/OpenSourceSwarm) which has 10 steps. It also adds support for: - assistants_v2 - retreival / file_search - streaming (get_completion_stream) - handles function calling better for models that do not technically support it by using (litellm prompting technique)[https://litellm.vercel.app/docs/completion/function_call#adding-function-to-prompt] @VRSEN I added this to a new directory `AstraOpenSourceSwarm`, if you'd rather me use the old `OpenSourceSwarm` directory let me know.