Keep all component registrars (#433)
Keep all component registrars (#433)

Component registrars are only referenced from metadata attributes in manifest
files, which can lead to them getting stripped by Proguard otherwise, resulting
in component lookup failures at runtime.
firebase/firebase-android-sdk,firebase/firebase-android-sdk,firebase/firebase-android-sdk,firebase/firebase-android-sdk,firebase/firebase-android-sdk,firebase/firebase-android-sdk,firebase/firebase-android-sdk,firebase/firebase-android-sdk