Deprecated feature use package=

[Teut2711]

Hello,
The package= attribute of the manifest file is deprecated. Please either help me submit a pull request or fix it. Thank you. I can try fixing it but I need to know where the com.x.z stuff is located at the least to get started.

https://github.com/react-native-community/cli/blame/134e23e0d9a407006bed508da3f523a855dae5b5/packages/cli-platform-android/src/config/getAndroidProject.ts#L83