fix: prevent api provider race condition, defer loading state update

[mrMetalWood]

Reproduced and confirmed problem and solution of #968 and applied suggested fix

Summary

Fixes an APIProvider race when google.maps.importLibrary is already installed by an external loader, but the Maps JavaScript API has not finished loading yet.

Previously, the external-loader fast path marked the API as LOADED before awaiting importLibrary('core') and importLibrary('maps'). This allowed provider effects and child components to run too early, causing errors such as google.maps.Settings is undefined or google.maps.Map is not a constructor.

Changes

• Wait for required libraries to resolve before setting APILoadingStatus.LOADED in the external-loader fast path.
• Add a regression test for externally installed google.maps.importLibrary with google.maps.Settings initially unavailable.

closes #968

[usefulthink]

Thanks! Seems like a simple enough fix that we can release it right away.

[cramt]

amazing, thanks for the quick fix ❤️