Web API for tunnels
Part of #81388

Fixes #83209

**Bug**
The extension page currently uses hardcoded height values for the header. This height breaks if the extension is recomended

**Fix**
Use flex layout instead

For #88313

Also log updateGraph on `completions.execute` instead of as its own event

We are also exproting other values/types, so use a named export instead

Fixes #88313

* Add call hierarchy support for TypeScript 3.8

* Add version dependent registration for call hierarchy provider

* Revert TS version, PR feedback

and fix related bugs

Fixes #88060

Part of #88244

Fixes #88059

fixes #88240