Improving the quality of icons for Android

Fix https://bugs.kde.org/show_bug.cgi?id=463043

I just modified ic_launcher and not ic_launcher_next.

I didn't actually compile and allow to test because configuring the environment is too difficult. I used Android Studio to create a new empty project then generated the icon and tested it. This pr is just changing the icon, so it shouldn't affect anything. Right?

I tested it using pipelines, which can support compilation and provide correct results.

Preview

Links

https://developer.android.com/studio/write/create-app-icons https://developer.android.com/distribute/google-play/resources/icon-design-specifications?hl=zh-cn