Add Code/Test coverage

[create-issue-branch[bot]]

Tools to use:

• grcov: Rust coverage tool by Mozilla/Rust makers
• rust-grcov: GitHub Action to run grcov on a repository
• codecov (codecov.io): Code coverage analyse tool & WebUI closes #129

[codecov[bot]]

Codecov Report

:exclamation: No coverage uploaded for pull request base (main@b538fcd). Click here to learn what that means. The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #130   +/-   ##
=======================================
  Coverage        ?   98.00%           
=======================================
  Files           ?       14           
  Lines           ?       50           
  Branches        ?        0           
=======================================
  Hits            ?       49           
  Misses          ?        1           
  Partials        ?        0           

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