For #79144

Currently we duplicate information for the `editor` and `workbench` configuration nodes in a few places. This change extracts some of those to be constants instead

Fixes #79425

Part of #74250

- Extend `Disposable` in classes where it makes sense
- Use `DisposableStore` for lists of disposables
- Make `combinedDisposable` take arguments instead of an array (so that you can't pass in an array and then modify the array after the fact)