feature: generate ideas with an LLM

[nwittstruck]

Further Notes

As an experiment, we'd like to allow users to generate ideas for brainstormings with an LLM.

We'll stick to the OpenAI API Chat Completions design, however, we should make sure it's usable with other LLM API endpoints that follow the OpenAI API design.

Possible Implementation

• Use openai_ex
• Generate ideas with a simple prompt asking for ideas for a given title in JSON format
• Add a simple button that does not allow configuration to a brainstorming when AI is enabled
• Check user locale to generate correct prompt

Follow-up questions:

• Should we allow admins to disable AI for a brainstorming?

Checklist

• [ ] Add feature / enhancement
• [ ] Make sure that it works based on user locale
• [ ] Add test
• [ ] Deploy on staging