[Feature] - Export report in various formats

[yuval-qf]

Describe the solution you'd like
Support exporting the output report from a set of supported formats based on a user's choice:

• json
• yaml
• html

Suggested implementation:

1. Support these export formats
2. Add support for the format argument in the /llm/summary server endpoint. This param should be optional.
3. Add an exported_format: str | None to the ServerSummaryGenerationResponse model. (feel free to find a better name)
4. Add support for reading and saving the exported_format in the various client-side (Gradio, cli, tui)