Add "pure annotation" to recipes and sprinkles

[kaorun343]

Background

Currently, the values exported from *.css.js and generated by recipes() and createSprinkles(...args)() are calling some runtime functions in bundled files. For instance, recipes() calls createRuntimeFn.
So, if these values are not used in production code, the JavaScript bundlers such as esbuild and webpack does not remove them because calling a function might have side effects.

var todoListItem = createRuntimeFn({
  defaultClassName: 'root',
  variantClassNames: {
    active: {},
    completed: {}
  }
})

Idea

So, I hope that vanilla-extract plugin adds /* @__PURE__ */ or /* #__PURE__ */ annotation to exported values.

• https://webpack.js.org/guides/tree-shaking/
• https://esbuild.github.io/api/#pure

var todoListItem = /* @__PURE__*/ createRuntimeFn({
  defaultClassName: 'root',
  variantClassNames: {
    active: {},
    completed: {}
  }
})

This new feature is useful when we build an UI library with vanilla-extract. Some components will use recipes in order to show multiple styles. All of them are not used in the same application, so those annotations will save the aplication's bundle size and performance.