Add coverage report action with cargo-llvm-cov & Codecov.

[gendx]

Pull Request Overview

This pull request adds code coverage report using cargo-llvm-cov, uploaded to Codecov.

Fixes #84.

Testing Strategy

This pull request was tested by checking whether the GitHub Action works.

Supporting Documentation and References

• https://github.com/codecov/example-rust
• https://lib.rs/crates/cargo-llvm-cov

TODO or Help Wanted

N/A

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (master@4989abd). Click here to learn what that means.
Patch has no changes to coverable lines.

Additional details and impacted files

@@            Coverage Diff            @@
##             master      #86   +/-   ##
=========================================
  Coverage          ?   86.83%           
=========================================
  Files             ?       19           
  Lines             ?     2484           
  Branches          ?        0           
=========================================
  Hits              ?     2157           
  Misses            ?      327           
  Partials          ?        0           

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[gendx]

Based on the analysis of the reports on Codecov, llvm-cov yields much better results than grcov.