New features for Hayhooks

[mpangrazzi]

This is a sort of a "Roadmap part 2" for Hayhooks. I will list here any possibile improvements with a rough estimation of implementation difficulty.

🟥 - difficult
🟨 - medium
🟩 - easy
🟪 - to investigate

• 🟩 Add examples to programmatically create an hayhooks instance (to add custom routes or middlewares)
• 🟩 Add an overwrite option to update a pipeline without the need of restarting the server
• 🟨 Support file uploads (e.g. for indexing pipelines)