Set the "default prompt" per project in settings.json

[brmassa]

AI prompt library is very good. For those that work on different types of projects (like rust, dotnet, markdown, python), the default is different and there is no much sense. Would be nice to use settings.json to allow each project to use a given prompt as its default.

• a new option in settings.json with either the prompt title (A) or the prompt text (B)
• in case another prompt is mentioned/nedded, a fallback in case the prompt is not available (in case we share the .zed folder in the repo but the user that cloned the project do not have the prompt)
• warning in case above. Maybe a "trust this project" dialog like VSCode?
• bonus: ability to include prompts in the .zed, so it could be embedded/shared in the project