[Services] Use shared services CMake project from tunnelbroker

Summary: Use shared services library now that it's exported.

Test Plan:
If you're running this on mac, you will also need later fixes for Clang + MacOS.

Please checkout D4766 then run the below workflow:

Docker workflow:

docker build . -f services/tunnelbroker/Dockerfile

Nix worfklow

nix develop
cd services/tunnelbroker
mkdir build && cd build && cmake .. && make

Reviewers: atul, max, karol

Reviewed By: atul

Subscribers: ashoat, tomek, adrian, abosh

Differential Revision: https://phab.comm.dev/D4757