codecov: Ignore all files containing "mock"
codecov: Ignore all files containing "mock"

Now that we're using mockery more aggressively the codebase is strewn
with auto-generated mock files that shouldn't be counted toward code
coverage.

mmussomele/quilt,NetSys/quilt,mmussomele/quilt,kayousterhout/quilt,ejj/quilt-dev,LuiseV/quilt,kayousterhout/quilt,LuiseV/quilt,tejasmanohar/quilt,kklin/kelda,NetSys/quilt,ejj/quilt-dev,LuiseV/quilt,quilt/quilt,mmussomele/quilt,LuiseV/quilt,kklin/kelda,kelda/kelda,quilt/quilt,kayousterhout/quilt,kklin/quilt,LuiseV/quilt,ejj/quilt-dev,PenguinToast/quilt,PenguinToast/quilt,kklin/kelda,PenguinToast/quilt,mmussomele/quilt,kelda/kelda,quilt/quilt,tejasmanohar/quilt,kklin/kelda,kelda/kelda,NetSys/quilt,mmussomele/quilt,NetSys/quilt,kayousterhout/quilt,tejasmanohar/quilt,PenguinToast/quilt,kklin/quilt,tejasmanohar/quilt,kklin/quilt,kklin/quilt,NetSys/quilt,kelda/kelda,PenguinToast/quilt,mmussomele/quilt,ejj/quilt-dev,quilt/quilt