The proto definitions may be needed at build time to generate appropriate
configs for the modules. Unbundled ART branches do not include
packages/modules/SdkExtenstion in their manifest; so put the proto in a
project that should be visible to all unbundled modules.
Move any relevant tools to packages/modules/common/tools as well.
Bug: 180105615
Test: m nothing
Change-Id: I4efa4300553af6b321f46adb29b8cc90e4556955
