Summary:
`react-native link` often fails due to the wrong manifest being used when you use a debug manifest. `findManifest` returns `debug/AndroidManifest.xml` instead of `main/AndroidManifest.xml`. And the debug manifest usually does not have the package name defined so `projectConfigAndroid` throws a cryptic "Cannot read property 'replace' of undefined" error.
This fixes the issue by throwing a more user friendly error and providing a `manifestPath` userConfig.
This is mostly based on comments to #10050.
Closes https://github.com/facebook/react-native/pull/13373
Differential Revision: D4945690
Pulled By: shergin
fbshipit-source-id: b177f916fd4799c873d2515c18cbb87bef3203f0