chore: switch reporters from util.inherits to ES2015 classes

[JoshuaKGoldberg]

PR Checklist

• Addresses an existing open issue: continues 🐛 Bug: remove util.inherits / convert to classes #5025
• That issue was marked as status: accepting prs
• Steps in CONTRIBUTING.md were taken

Overview

Switches Base, the reporters that extend from it, and class-likes in those files.

This one is more involved than the others, as existing test helpers need to be updated. The tests were previously doing some funky .call() stuff with scopes. Now they use an intermediate class to assign extensions to a new instance.

🤎

[JoshuaKGoldberg]

Closing for now since #5025 is blocked on us being ready for a next major version. We can reopen later.

[coveralls]

coverage: 94.288% (-0.07%) from 94.357%
when pulling 53c0d00 on JoshuaKGoldberg:inherits-to-class-reporters
into 579e047 on mochajs:main.

[JoshuaKGoldberg]

Reopening now that we're working on v12 (#5357).

[JoshuaKGoldberg]

Ah, I remember this now: the unit tests needed to be massaged quite a bit too. I'll do that.

[codecov]

Codecov Report

❌ Patch coverage is 80.72289% with 128 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.74%. Comparing base (5574738) to head (83dfcc3).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/reporters/html.js	1.60%	123 Missing ⚠️
lib/reporters/landing.js	92.10%	3 Missing ⚠️
lib/reporters/base.js	97.61%	1 Missing ⚠️
lib/reporters/progress.js	97.43%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5180      +/-   ##
==========================================
- Coverage   88.89%   88.74%   -0.15%     
==========================================
  Files          66       66              
  Lines        4771     4744      -27     
  Branches      976      976              
==========================================
- Hits         4241     4210      -31     
- Misses        530      534       +4     

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[mark-wiemer]

Generally pretty good, just a couple points of confusion :)

[mark-wiemer]

Test failure is transient git issue, tests pass locally, all other tests pass, merging :)