Add code coverage workflow

[jphickey]

Add a github workflow similar to the code coverage workflow for CFE/CFS that builds the software, executes coverage tests, and checks the results.

Example for CFE is here: https://github.com/nasa/cFE/blob/be88a07313ff3b579c8abaef4b4a9085e74aabdf/.github/workflows/code-coverage.yml

A similar process can be done for bplib

[jphickey]

I finished developing the workflow for the build and functional test - now submitted in PR #203

However - the bplib build currently does not currently have a different enable switch for the coverage and functional tests, we either build all of them or none of them based on the BPLIB_ENABLE_UNIT_TESTS option.

Therefore, when running the functional tests, the workflow in PR #203 is also running the coverage tests (because they are together) and hence it only made sense to also include the coverage report here in this as well.

Example run and report can be seen in my fork here: https://github.com/jphickey/bplib/actions/runs/3420685624/attempts/1#summary-9365030655

My recommendation would be to close this issue for now, I don't think we need a separate workflow specifically for the coverage testing at this time.