Fixes iOS APNS not getting set on repeat boots, adds checkNotificatio…

[BBlashko]

…nStatus function

The changes here include:

Android:

• Adds checkNotificationStatus function to get the notifications status denied/authorized verdict

iOS

• Adds checkNotificationStatus function to get the notifications status not determined/denied/authorized/provisional/ephemeral verdict
• Fixes an issue with the APNS Token. On repeat boots the APNS token is set to nil

[wswoodruff]

Thank you for this, I was hoping to find checkNotificationStatus in PRs!

[wswoodruff]

@chemerisuk Bump on this PR plz!

If the code looks good, I guess only remaining thing is to update the README