fix(eslint-plugin): [method-signature-style] handle multiline params

[bradzacher]

Fixes #1857

Whilst I was there, I also added support for preserving the delimiter, because why not

[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!

---

🙏 Please, if you or your company is finding typescript-eslint valuable, help us sustain the project by sponsoring it transparently on https://opencollective.com/typescript-eslint. As a thank you, your profile/company logo will be added to our main README which receives thousands of unique visitors per day.

[codecov]

Codecov Report

Merging #1861 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1861   +/-   ##
=======================================
  Coverage   94.71%   94.71%           
=======================================
  Files         161      161           
  Lines        7338     7347    +9     
  Branches     2101     2103    +2     
=======================================
+ Hits         6950     6959    +9     
  Misses        165      165           
  Partials      223      223           

Flag	Coverage Δ
#unittest	94.71% <100.00%> (+<0.01%)	⬆️

Impacted Files	Coverage Δ
.../eslint-plugin/src/rules/method-signature-style.ts	91.48% <100.00%> (+2.01%)	⬆️