Draft: Implement minimal LicensingService

Summary

Implement minimal LicensingService for 3rd party apps support.

Description

Some apps are using the Google App Licensing feature: https://developer.android.com/google/play/licensing

Implemented ILicensingService & ILicenseResultListener interfaces with the minimal logic.

For now, we always answer the listener that the license result is correct.

Issues

e/backlog#2525