feat(eslint-plugin): add extension rule lines-between-class-members

[yeonjuan]

Fixes #1610

[typescript-eslint]

Thanks for the PR, @yeonjuan!

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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 #1684 into master will decrease coverage by 0.00%.
The diff coverage is 92.30%.

@@            Coverage Diff             @@
##           master    #1684      +/-   ##
==========================================
- Coverage   93.93%   93.93%   -0.01%     
==========================================
  Files         171      172       +1     
  Lines        7816     7829      +13     
  Branches     2243     2245       +2     
==========================================
+ Hits         7342     7354      +12     
  Misses        217      217              
- Partials      257      258       +1     

Flag	Coverage Δ
#unittest	93.93% <92.30%> (-0.01%)	⬇️

Impacted Files	Coverage Δ
...nt-plugin/src/rules/lines-between-class-members.ts	92.30% <92.30%> (ø)

[bradzacher]

Thanks for doing this!

Haven't reviewed the code yet, but just some quick feedback on the docs.

Example of how we like to do extension rule docs now a days - instead of copy-pasting the ESLint docs, just list the changes we're adding to the rule, and link out to the ESLint docs.
That way we don't have to worry as much about getting out of date.

https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/docs/rules/func-call-spacing.md

I.e. in this case, you can just list the new option and how it works, and that covers it.

[yeonjuan]

@bradzacher
Thank you for the quick response and feedback. :). I changed it.

[bradzacher]

Thanks! code mostly LGTM - a few linting errors to fix before this can be merged.

[bradzacher]

LGTM - thanks!