[Brave Leo]: Add (static) conversation starters

[LorenzoMinto]

Design file: here
Library file for component details: here

Options:

• Write a memo
• Generate interview questions
• Create a study plan
• Create a project timeline
• Develop a marketing strategy
• Outline a presentation
• Help me brainstorm
• Craft a professional email
• Formulate a business proposal

Behaviour:

1. For conversations without attachable context (new tab page, internal pages, new full page conversations), show 4 Conversation Starters. These are sampled at random from a list of static options (described above).
2. For conversations with attachable context (sidebar + webpage), show "Summarise this page" and "Suggest Questions" (without ellipsis) in the new style. If context is detached, show conversation starters.

[petemill]

Looks like the generated questions should also have the same new style? And that includes an emoji for each one?

• @LorenzoMinto we'll need the conversation API (and BYOM client-side prompts) prompts to return these
• @aguscruiz do we need a version without the emoji if we can't generate one?

[aguscruiz]

If we can't generate an emoji we could just use this one as the placeholder one 💬