feat: move .eslintignore into .eslintrc.cjs ignorePatterns

[JoshuaKGoldberg]

PR Checklist

• Addresses an existing open issue: fixes 🚀 Feature: Move .eslintignore into ESLint config #1261
• That issue was marked as status: accepting prs
• Steps in CONTRIBUTING.md were taken

Overview

Removes the .eslintignore file and its templating. Instead adds the ignorePatterns entry in .eslintrc.cjs and its templates.

Also adds .eslintignore to the list of cleared unnecessary files.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (81fb3eb) 94.81% compared to head (0673629) 94.80%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1262      +/-   ##
==========================================
- Coverage   94.81%   94.80%   -0.01%     
==========================================
  Files         104      103       -1     
  Lines        5808     5799       -9     
  Branches      492      492              
==========================================
- Hits         5507     5498       -9     
  Misses        300      300              
  Partials        1        1              

Flag	Coverage Δ
create	70.04% <85.71%> (-0.05%)	⬇️
initialize	42.23% <14.28%> (-0.01%)	⬇️
migrate	69.86% <85.71%> (-0.05%)	⬇️
unit	75.58% <100.00%> (-0.03%)	⬇️

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[github-actions]

🎉 This is included in version v1.55.0 🎉

The release is available on:

• GitHub releases
• npm package (@latest dist-tag)

Cheers! 📦🚀