Fixes #43574

- Avoids extra checks when response cannot be null

- Make async
- extract some methods

Break up the concept of normalizing a path and trying to get the on disk path of a resource. Needed for handling case insensitivity

This helps prevent misuse of the API objects and will allow for more declarative apis

Fixes #28214

- Use await
- Use for of

Fixes #26418

Allows enabling or disabling the references code lenses in either javascript or typescript. Previously, the setting enabled it in both language automatically. Enable the code lenses in ts files by default

Fixes #24209

**Bug**
Currently, for the js/ts references code lens, even if there are zero references you can click on the lens. This display an empty peek view

**Fix**
Allow code lenses to only register a title for the lens with no actual backing command

* Prototype of Implementations Code Lens Provider for TypeScript

Adds a prototype code lens that shows the number of implementations for interfaces and abstract classes. This shares a lot of code with the references code lens provider, so I extracted most of the common stuff into a base class.

* Support children of interfaces

* Add setting to control implementations code lens