* Add Type Definition Provider API

Adds a new API to support type definition providers and adds an initial type definition provider for TypeScript

* Fix comment

* Addressing comments

* Fixer menu option ordering

* Added simple test

* Rename TypeDefinitionProvider to TypeImeplementationProvider

**bug**
In #18346, I originally called the new go to implementation provider api `ImplementationProvider` which we then decided to rename to `TypeDefinitionProvider`. At the time, I didn't realize that a type definition was actually its own, unrelated concept.

**Fix**
Rename `TypeDefinitionProvider` to `TypeImplementationProvider` to make it clear what the purpose and use of this api is.

* Fix a few names in comments

Adds an initial implementation of scroll synrconization from the markdown preview to the editor. When the preview is scrolled, automatically scrolls the editor to reveal the same location.

This required adding a new supported reveal type `AtTop` in our API. This is already supported and used internally, but not really exposed in the public apis (except for the `revealLine` command).