flutter 多渠道模板
flutter build apk --flavor channelA --dart-define=CHANNEL=channelA
flutter build apk --flavor channelB --dart-define=CHANNEL=channelB
flutter build appbundle --flavor channelA --dart-define=CHANNEL=channelA
flutter build appbundle --flavor channelB --dart-define=CHANNEL=channelB
flutter build ipa --flavor channelA