chore: added test coverage and upload codecov

[richardcase]

What this PR does / why we need it:

Track the code coverage over time. This change adds a unit-test with coverage makefile target and updates the test GHA workflow to upload the results to codecov

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #80

Special notes for your reviewer:

Checklist:

• squashed commits
• includes documentation
• adds unit tests
• adds or updates e2e tests

Release note:

Test coverage tracking with codecov integration

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (main@a1aff98). Click here to learn what that means.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #79   +/-   ##
=======================================
  Coverage        ?   67.41%           
=======================================
  Files           ?       23           
  Lines           ?      758           
  Branches        ?        0           
=======================================
  Hits            ?      511           
  Misses          ?      184           
  Partials        ?       63           

---

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[bigkevmcd]

Looks fine to me!

[richardcase]

Thanks @bigkevmcd