Make scoped style tranform configurable

[fisker]

When compiling<style scoped>, it will be nice if it's configurable.

Eg. inject data-v-foo to element, but use .bar:where([data-v-foo]) instead of .bar[data-v-foo].

In miniprogram, it's not possible to inject an attribute, but we can add an extra class and compile selector to .bar.data-v-foo to make the scoped style work.