* Adding SiriKit permissions (#1140)

* Adding SiriKit permissions

* Fix tests

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Co-authored-by: Maurits van Beusekom <maurits@vnbskm.nl>

* Reserves the assistant permission on no-op platforms

* Adds support to example application

* Remove pubspec overrides

* Fix formatting

* Add support for Permission.assistant to the app facing package.

* Fix formatting

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Co-authored-by: Baptiste DUPUCH <baptiste.dupuch@gmail.com>