Code coverage numbers should include all C files

Currently, the code coverage is only for C files linked into unit_tests.exe and ebpf_client.exe.

All files that are not used to build these are then excluded from our code coverage totals.

The ideal scenario would be to have all C files included in our code coverage numbers.

Start by examining the code-coverage configuration and the build inputs for unit_tests.exe and ebpf_client.exe. Determine how C files are selected and how unused files are excluded. Done means the coverage totals include all C files, including those not linked into either executable.

Written by the indexing model from the issue text.