Replace stylistic rules with prettier plugin

[fregante]

Stylelint does a less-than-stellar job at formatting, and they’re fine with it:

• Fix false negatives for multiline selectors in indentation stylelint/stylelint#3461
• Fix false positives for parens in selectors in indentation stylelint/stylelint#5181

So what do you think about adding this plugin to the config to defer this job to Prettier by default?

https://github.com/prettier/stylelint-prettier

[sindresorhus]

I personally don't plan to use Prettier, but I'm happy to have the current config split into stylistic and non-stylistic if that would help.