feat(eslint-plugin): add extension rule no-loop-func

[bradzacher]

Fixes #2448

[typescript-eslint]

Thanks for the PR, @bradzacher!

typescript-eslint is a 100% community driven project, and we are incredibly grateful that you are contributing to that community.

The core maintainers work on this in their personal time, so please understand that it may not be possible for them to review your work immediately.

Thanks again!

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[codecov]

Codecov Report

Merging #2490 into master will increase coverage by 0.02%.
The diff coverage is 96.36%.

@@            Coverage Diff             @@
##           master    #2490      +/-   ##
==========================================
+ Coverage   92.82%   92.84%   +0.02%     
==========================================
  Files         289      290       +1     
  Lines        9294     9349      +55     
  Branches     2600     2620      +20     
==========================================
+ Hits         8627     8680      +53     
  Misses        321      321              
- Partials      346      348       +2     

Flag	Coverage Δ
#unittest	92.84% <96.36%> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
packages/eslint-plugin/src/configs/all.ts	100.00% <ø> (ø)
packages/eslint-plugin/src/rules/no-loop-func.ts	96.36% <96.36%> (ø)

[lencioni]

Thanks for landing this so quickly!