
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 moves the `usesSwiftPackageManager` property from the platform-agnostic `Project` to the platform-specific `IosProject` and `MacOSProject`. This will allow the `IosProject` and `MacOSProject` to return different values for `usesSwiftPackageManager` in the future. For now, both of these projects will always return the same value. Part of https://github.com/flutter/flutter/issues/151567