text: Title: Add txtai agents 🚀
  Body: This will add agents to txtai. We'll build on the [Transformers Agents framework](https://huggingface.co/docs/transformers/en/agents) in combination with [txtai's LLM pipeline](https://neuml.github.io/txtai/pipeline/text/llm/).
  
  The goals of this framework are:
  
  - Easy-to-use
  - Integrate with pipelines, workflows and embeddings databases
  - Support all LLM backends (tranformers, llama.cpp, API integrations)
  - Support use cases like self-correcting RAG, multi-source RAG and real-time data integration
  
  The following issues cover this change.
  
  - [x] #808 
  - [x] #809
  - [x] #810 
  - [x] #811
  