UX improvements for automated typings acquisition

[mjbvz]

Adopt new status code API to improve automatic typing acquisition UX

[mjbvz]

Opened microsoft/TypeScript#12540 to track the addition of the notifications we need from TS to support this

[mjbvz]

Initial work for rejecting completion item promise was completed with #17098. We now need to surface these rejection message in some way and also look into adopting this pattern in other places.