Add CI action for code coverage for `tbf-parser`

[eva-cosma]

A CI action that does a code coverage report for tbf-parser. We might, in the future, also expand it for the main code.

This action requires quite a lot of explanation, so if you see this it means I haven't had the time to edit this issue to add these details. Contact me @george-cosma . See also https://github.com/DLR-FT/wasm-interpreter/blob/72e7cf53e1c171051d5e970af45e389c9a58dd02/.github/workflows/nix.yaml#L59

[eva-cosma]

@addrian-77 I unassigned you, I need you to focus on your current open PRs / the new issue I gave you