Reranker models

[dcieslak19973]

Is your feature request related to a problem? Please describe.
Allow the curator to use specific reranker models like those from AWS or Cohere

Describe the solution you'd like
Only use

            response = await create_chat_completion(
                model=self.researcher.cfg.smart_llm_model,
                messages=[
                    {"role": "system", "content": f"{self.researcher.role}"},
                    {"role": "user", "content": rank_sources_prompt(
                        self.researcher.query, source_data, max_results)},
                ],
                temperature=0.2,
                max_tokens=8000,
                llm_provider=self.researcher.cfg.smart_llm_provider,
                llm_kwargs=self.researcher.cfg.llm_kwargs,
                cost_callback=self.researcher.add_costs,
            )

As a fallback if no reranker model is specified

Describe alternatives you've considered
N/A

Additional context
Purpose-built reranking models likely outperform prompts

[ElishaKay]

cc @assafelovic