feat: sort media queries option

[cossssmin]

Allow opting in to media query sorting and merging through the css.sortMediaQueries config option:

export default {
  css: {
    sortMediaQueries: true,
  }
}

Can be an object that configures postcss-sort-media-queries:

export default {
  css: {
    sortMediaQueries: {
		sort: 'mobile-first',
    },
  }
}

Disabled by default.

[cossssmin]

Think this looks better:

export default {
  css: {
    media: {
      sort: 'mobile-first',
    },
  }
}

And as long as media is not a falsy value, media queries will be merged:

export default {
  css: {
    media: {
      merge: true,
    },
    // same as `media: true`
  }
}