[Services] Clang fixes for services/lib/src

Summary:
Clang is a bit more pedantic. Make it happy.

Occurred to me that this was never an existing workflow.
So I made it into another diff.

Allows for D4489 to be built from a MacOS device

Test Plan: Follow nix test plan from D4489 on a mac device

Reviewers: atul, karol, max

Reviewed By: atul

Subscribers: ashoat, tomek, adrian, abosh

Differential Revision: https://phab.comm.dev/D4761