[ios_platform_images] Add Swift Package Manager compatibility to ios_platform_images #146909
Description
Prerequisites:
- Add Swift Package Manager as new opt-in feature for iOS and macOS #146256
- Update packages CI to test Swift Package Manager integration for plugins #146901
Follow "Converting an existing Swift Flutter Plugin to a Swift Package" instructions to make ios_platform_images plugin compatible with Swift Package Manager and CocoaPods.
To validate all is working, run the following commands
// Disable swift package manager
flutter config --no-enable-swift-package-manager
// Build example with CocoaPods
dart run script/tool/bin/flutter_plugin_tools.dart build-examples --ios --packages=ios_platform_images
// Build example with swift package manager
dart run script/tool/bin/flutter_plugin_tools.dart build-examples --ios --swift-package-manager --packages=ios_platform_images
// Run native tests
dart run script/tool/bin/flutter_plugin_tools.dart native-test --ios --packages=ios_platform_images