Optimize code coverage collection (#84)

* :shell: Track script for collecting code coverage

* :memo: Document using new code coverage script

* Rebase `ci-cd/optimize-code-coverage` on `eb855d0`

> Blame @S0AndS0 if anything was broken due to merge conflict resolution

* Ignore paths under `./target/` sub-directory

* Tell `cargo-tarpaulin` to ignore another test

* :shell: Attempt excluding artifacts from tarpaulin

:shrug: but may require _more_ post-process piped filtering

* :facepalm: Steal code from `origin/main` rebase

> `3d0be663d116fff3c502c52ff31c08e288214be4`