VS Code integrated outline view

[KamasamaK]

https://github.com/Microsoft/vscode/labels/outline

This issue is just for informational/tracking purposes. It's possible that the new functionality could replace this extension, but if not then it is also providing additional APIs that could improve this extension.

Some of the issues are still up for discussion if anyone has any ideas on how to improve the outline capabilities.

[patrys]

I'm happy to deprecated this in favor of the built-in one once it leaves the "preview" phase. Unfortunately most APIs used byt the new feature are private ones and it's still impossible for me to provide clickable elements without automatically expanding them or to have a search box above the tree.

What I am planning to implement is incorporating various reported folding regions into the tree. Let's see where that takes us once the API becomes available (maybe the official outline will follow our steps).