Replace nyc with c8 for code coverage

[ElJocko]

c8 is a drop-in replacement for the abandoned(?) Istanbul/nyc code coverage tool. Differences:

• c8 uses the native v8 code coverage
• c8 uses a different metric for lines/statements covered which will result in a one-time jump in the coverage recorded (it counts every line, whether it's code, a comment, or blank)
• c8 is actively maintained (nyc hasn't been updated in almost 3 years)

Closes #255

[codecov[bot]]

Codecov Report

Patch and project coverage have no change.

Comparison is base (8e5bf7f) 55.18% compared to head (8e5bf7f) 55.18%.

:exclamation: Current head 8e5bf7f differs from pull request most recent head e129744. Consider uploading reports for the commit e129744 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #256 +/- ## ======================================== Coverage 55.18% 55.18% ======================================== Files 118 118 Lines 6632 6632 Branches 1384 1384 ======================================== Hits 3660 3660 Misses 2216 2216 Partials 756 756 ```

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[sonarcloud[bot]]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication