Add Swift Package Manager support

Hello,

Flutter is migrating to Swift Package Manager. Please add Swift Package Manager support to your plugin.

Flutter will eventually deprecate and then remove support for CocoaPods. Adding Swift Package Manager support future-proofs your plugins.

How to add Swift Package Manager support to your plugins
You can find the migration guide here: https://docs.flutter.dev/packages-and-plugins/swift-package-manager/for-plugin-authors#how-to-add-swift-package-manager-support-to-an-existing-flutter-plugin

If you run into issues or have questions, please reach out to the Flutter team. You can send a message to the #hackers-ios channel on Flutter’s discord, or open a GitHub issue.

Thank you for your wonderful contributions to the Flutter ecosystem!

Why is Flutter migrating to Swift Package Manager?
CocoaPods is now in maintenance mode.

Swift Package Manager support is one of Flutter’s most requested features: https://github.com/flutter/flutter/issues/33850.

Flutter's Swift Package Manager integration has several benefits:

Access to the Swift package ecosystem. Flutter plugins can use the growing ecosystem of Swift packages.
Simplifies Flutter installation. Swift Package Manager is bundled with Xcode. In the future, you won’t need to install Ruby and CocoaPods to target iOS or macOS.

Start with the linked Flutter migration guide and inspect this plugin's existing CocoaPods integration. Confirm the required Swift Package Manager support for the plugin, then verify it using the checks or validation steps described in the guide.