Integrate methods used by NHS (non Exposure Notification API) for successful iOS background scanning

[waldobeest]

Given the TODO status of the iOS background scanning and advertising, I have been looking for a solution to allow for background iOS operations, without the need for the Apple Exposure Notification API (since it is locked to official government use only).

This article unpacks how the current NHS app can run iOS-to-Android and iOS-to-iOS in the background.

Code for this can be found here: https://github.com/nhsx/COVID-19-app-iOS-BETA

I will deeper into how rn-contact-tracing is currently accessing Bluetooth, as opposed to the NHS app above, and possibly make suggestions/ PR for getting this behaviour into rn-contact-tracing.

Do you guys think this is on the right track?