Adds chat extension prototype. Closes: #43

[Adam-it]

🎯 Aim

The aim is to create a prototype of a CLI chat participant to play around with this feature in it's early release state

📷 Result

🔗 Related issue

Closes: #43

[Adam-it]

@waldekmastykarz please check this draft PR along with the above review comments with my 'notes' from our early tests of this feature. Any comment or further testing result on this feature is more than welcome! If you are interested in more this then please go over the docs, mainly those two pages are most important https://code.visualstudio.com/api/extension-guides/chat https://code.visualstudio.com/api/extension-guides/language-model

[Adam-it]

@waldekmastykarz if you want to build this extension locally please:

• pull this branch
• be sure you are using node v18 or higher
• install @vscode/vsce package
• in the context of the extension run the vsce package command

[Adam-it]

a similar change done i SPFx Toolkit were the implementation is waaay better and has less duplicated code https://github.com/pnp/vscode-viva/pull/240/files#diff-60c6e141f6c2a19f589374b7b99e660cccf11a41fcb29f480f8892550d70ed17