Add AI support for playbook run status

[jespino]

Summary

This PR adds support for AI-generated status updates in Playbook runs. It exposes the necessary components and APIs to allow the Playbooks plugin to leverage the AI plugin's capabilities for generating status updates.

Key Changes

• Added a new API endpoint /playbook_run/:playbookrunid/generate_status that generates status updates for playbook runs using AI
• Created a new prompt template for playbook run status generation that can:
  • Follow a specific template format if provided
  • Take additional instructions to guide the generation
  • Consider previous messages for context
  • Generate direct summaries without introductory text
• Exposed the bot selector component and bot loader hook for reuse in other plugins
• Added support for using different AI bots for status generation

Technical Details

• The status generation API accepts:
  • Instructions to guide the generation
  • Previous messages for context
  • Bot selection for using different AI models
• The API streams the generated content back to the client
• Added proper authorization checks for playbook run access
• The prompt template is designed to generate concise, relevant updates based on channel activity