FEAT: UI Assistants - Support function def

[MiNeves00]

Allow for defining the functions for Assistants in the UI.

• [ ] Clean up with Lint
• [ ] Generate the JSON openai wants
• [ ] Save these functions somewhere
• [ ] Check security concerns with running user code

Motivation On openai playground users cannot define functions easily. this would be a good upgrade and a reason for users to use our UI instead

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