Getting working with Preact

Seems `styleName` not being transformed to corresponding `className` when using `preact`. Tried to migrate same `babel-plugin-react-css-modules` config from existing React project but failed to get it working with Preact. Using `preact-compat` package.

Other issues (https://github.com/gajus/babel-plugin-react-css-modules/issues/200, https://github.com/gajus/babel-plugin-react-css-modules/issues/65) show notions of using Preact in their projects but no real evidence.

And slightly off-topic, but in case anyone stumbles upon `styleName` typings error when working with Preact, TypeScript and this plugin: https://github.com/DefinitelyTyped/DefinitelyTyped/issues/12040#issuecomment-480890380.