feat(firebase_messaging): Added 'criticalAlert' to notification settings.

[komaxx]

Enables apps to check whether the user permitted critical alerts (iOS only)

Description

The PR adds a critical to notification_settings.dart. This informs calling apps whether the user permitted the app to trigger critical alerts, which bypass the phone's "mute" and "focus" settings. Apple only.

The according flag criticalAlert was already part of the native ObjectiveC code but was not yet read in Dart. Just added that part.

Related Issues

• none

Checklist

• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• My PR includes unit or integration tests for all changed/updated/fixed behaviors (See [Contributor Guide]).
• All existing and new tests are passing.
• I updated/added relevant documentation (doc comments with ///).
• The analyzer (melos run analyze) does not report any problems on my PR.
• I read and followed the [Flutter Style Guide].
• I signed the [CLA].
• I am willing to follow-up on review comments in a timely manner.

Breaking Change

Does your PR require plugin users to manually update their apps to accommodate your change?

• Yes, this is a breaking change.
• No, this is not a breaking change.

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[russellwheatley]

Hey @komaxx, thanks for the PR! Could you rename to "criticalAlert" to match the iOS property?

[komaxx]

Hey @komaxx, thanks for the PR! Could you rename to "criticalAlert" to match the iOS property?

Absolutely! Done :)

[komaxx]

@russellwheatley If you don't mind, could you take another look?