Add Swift Package Manager support

[igordanilovski]

Because Flutter is migrating to Swift Package Manager I can't build the app for iOS.

In Flutter 3.27 release, Xcode throws following error: GeneratedPluginRegistrant.m:12:9 Module 'app_settings' not found

Flutter will eventually deprecate and then remove support for CocoaPods.

Is there any workaround for this or any scheduled implementation of Swift Package Manager?

[Mik77o]

It would be great to add support for SPM :)

[yanashenyang]

expectance