Mirror Requests using Intercepts, Chat Model in LLM Gateway, UI Improvements and Bug fixes

New Features & Improvements:

• Added support for chat type models in LLM Gateway
• Added support for mirroring request using intercepts
• Added support for artifact cache and download in service form
• Removed delete user functionality
• Removed last used column from notebooks

Bug fixes:

• Fixed images and plots loading issue in ML Repos
• Minor UI bug fixes