Implement a stub permission server for Brillo tier 1.

This will allow removing some existing hardcoded checks, like
https://cs.corp.google.com/android/frameworks/native/libs/binder/IServiceManager.cpp?l=70

Also add a .clang-format file for Android Framework C++ style.

Bug: 25663983
Change-Id: Icc4473a6f7b8c7395cdb167dc3fdbb2f076e5960