Add support to Swift Package Manager

[ziadsarour]

Describe your issue. If applicable, add screenshots to help explain your problem.

Add support to Swift Package Manager as recommended by Flutter : https://docs.flutter.dev/packages-and-plugins/swift-package-manager/for-plugin-authors

Steps to reproduce.

Nothing to reproduce

What is the expected result?

Swift Package Manager supported

Did you try our example app?

No

Is it reproducible in the example app?

Yes

Reproducible in which OS?

iOS

Flutter/Dart Version?

No response

Plugin Version?

All packages using Podfile