Summary: The `Error: Attempted to build clientId with invalid app: "` event shows up in our monitoring regularly, but it is unclear which kind of app is trying to connect, so adding some more info to the error, to be able to pin point it better a next time
Reviewed By: lawrencelomax
Differential Revision: D33982871
fbshipit-source-id: 34c2612a9fe86a6815f1cc655f6def1f734e4b1e
Summary: moved `app/src/server` to `flipper-server-core/src` and fixed any fallout from that (aka integration points I missed on the preparing diffs).
Reviewed By: passy
Differential Revision: D31541378
fbshipit-source-id: 8a7e0169ebefa515781f6e5e0f7b926415d4b7e9