Register public mesh research app's signing key and package name with Google Play
If we plan to develop a research app as part of #1817, register the package name and app signing key with Google Play before the end of July 2021 so we're not required to let Google manage the signing key.
https://android-developers.googleblog.com/2020/11/new-android-app-bundle-and-target-api.html
Subtask of #1817.