fix(messaging): initialize app props method to fix isHeadless property

[russellwheatley]

WIP - I have not been able to test properly (outside of preliminary tests) because the FCM gods are not with me today, and my messages are being blocked to my device when my app is in a quit state. Will try again soon unless someone else has it all set up and would like to confirm.

Description

• Created a initializeAppProps helper method. This ought to guarantee the isHeadless property is present in the properties passed to the component registered. i.e. registerComponent component. This is used when the app is in a quit state and receives a message via FCM for iOS. The setBackgroundMessageHandler is called and the app is also silently booted, this prop will allow the developer to return null based on isHeadless === true.

• The bug is a result of the application booting before the isHeadless property is added to the appProperties for the RCTRootView instance.

Related issues

fixes #3983

Release Summary

Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
  • Yes
• My change supports the following platforms;
  • Android
  • iOS
• My change includes tests;
  • e2e tests added or updated in packages/\*\*/e2e
  • jest tests added or updated in packages/\*\*/__tests__
• I have updated TypeScript types that are affected by my change.
• This is a breaking change;
  • Yes
  • No

Test Plan

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[mikehardy]

false negative on E2E in iOS this time (android ran clean!), I restarted it, will look at iOS next