feat: copilot new api VSCODE-550

[alenakhineika]

Description

• Create a MongoDB participant using the latest VSCode Language Model API
• Create the /query command that generated MongoDB queries and can open them in a new playground or run directly
• Call a generic handler if the participant called without a command

Checklist

• New tests and/or benchmarks are included
• Documentation is changed or added
• I have signed the MongoDB Contributor License Agreement (https://www.mongodb.com/legal/contributor-agreement)

Motivation and Context

• Bugfix
• New feature
• Dependency update
• Misc

Types of changes

• Backport Needed
• Patch (non-breaking change which fixes an issue)
• Minor (non-breaking change which adds functionality)
• Major (fix or feature that would cause existing functionality to change)

[Anemy]

lgtm, left one small question and suggestion. I'm thinking we'll be doing a good amount of iterating on prompts, response handling, and more so not a need for now.