[eslint-plugin] Split up `valid-styles`

[mellyeliu]

Constant ask from ESLint folks. Most common complaint with linting is that valid-styles as a rule is not descriptive and difficult to understand. It handles a lot of things: property validation, type checking, object structure validation, pseudo-selectors and at-rules, border shorthand expansion, and converts nonstandard properties to current ones.

There's also some duplication with valid-shorthands.

Let's consolidate and split up logic where it makes sense. There are some ESLint perf regressions from scanning styles multiple times so let's think through what makes sense

[jcperez-ch]

This got closed when landing the first merge, this issue is still open and in development.

[mellyeliu]

i think the git ui scans for "Fixes XXX" and closes regardless :D