3094: Push notifications quit state solution

[bahaaTuffaha]

Short Description

At the moment, push notifications are not correctly handled if the app is in a quit state on android (and most likely on iOS, too). The app only opens on the last opened page. In theory, this might also be a development issue though.

Proposed Changes

• Used setBackgroundMessageHandler instead of importFirebaseMessaging
• I don't think it needs unsubing like it was from my searching over internet.
• there was an error for jest about:

Invariant Violation: `new NativeEventEmitter()` requires a non-null argument. 

I solved it by jest.mock('react-native/Libraries/EventEmitter/NativeEventEmitter') according to here

Side Effects

• I hope none

Testing

Resolved Issues

Fixes: #3094

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