Description

1 Line Summary

Fix prompting again after closing notification permission prompt if site has its own ServiceWorker.

This PR fixes two things related to this issue:

requestNotificationPermission() - this was always returning undefined due to a conversion bug
getRegistration() - did not check if the service worker was a OneSignal one, resulting in wrong assumptions being made.

Added a unit test for requestNotificationPermission(), this was always returning undefined before the changes in the first commit.

[X] All the automated tests pass or I explained why that is not possible
[X] I have personally tested this on my machine or explained why that is not possible
[X] I have included test coverage for these changes or explained why they are not needed

Programming Checklist Interfaces:

Functions:

[X] Don't use default export
[X] All function signatures have return types
[X] Helpers should not access any data but rather be given the data to operate on.

Typescript:

Other:

[X] Iteration: refrain from using elem of array syntax. Prefer forEach or use map
[X] Avoid using global OneSignal accessor for context if possible. Instead, we can pass it to function/constructor so that we don't call OneSignal.context

[ ] I have included screenshots/recordings of the intended results or explained why they are not needed

This change is