Part of #75091

Fixes #72155

Adds a constant to the api that tracks the root path for resources inside of webviews. This is required because we will not be able to use `vscode-resource:` uris on the web. Our current approach is to rewrite the html we are given but there are almost certainly going to be cases where we don't get this quite right.

Adopts the new api for the markdown preview

Part of #75091

For #74846

Migrates from using the heap service to have an explicit lifecycle

Part of #75091

Fixes #75278

debt - decouple webviews from code insets, move things to /browser/-layer, change inset api proposal to push style, re #66418

* Rename user to author for Comment.

* Make Comment interface

* Fix #73170. Introduce CommentAuthorInformation

* Fix #73145. Update range properly.

* Comments API Finalization

* Provide API to get access to the workspace configuration file (#37421)

* fix untitled ID

* update docs