003135e2d0
In the future, it will be possible for Swift Package Manager to be enabled on one but not all platforms (see https://github.com/flutter/flutter/issues/151567#issuecomment-2455941279). This updates the `.flutter-plugin-dependencies` file format to separate iOS's and macOS's SwiftPM enablement. For now, these platforms will always have the same value. This `.flutter-plugin-dependencies` file is read by our CocoaPods scripts to determine whether we should use CocoaPods or not to inject plugins. Part of https://github.com/flutter/flutter/issues/151567