As part of the effort to tighten the API surface of
`TypeScriptServiceHost` in preparation for the migration to Ivy, I realized
some recently added APIs are not strictly needed.
They can be safely removed without sacrificing functionality.
This allows us to clean up the code, especially in the implementation of
QuickInfo, where the `TypeScriptServiceHost` is leaked outside of the
`LanguageService` class.
This refactoring also cleans up some duplicate code where the QuickInfo
object is generated. The logic is now consolidated into a simple
`createQuickInfo` method shared across two different implementations.
PR Close#34941
3414ef276e