Emit class components to circumvent `defaultProps` warnings

[Grohden]

trafficstars

I'm changing the code emission so that it emits class components so that we don't get defaultProps deprecated warnings anymore

This is all based on this suggestion here https://github.com/airbnb/babel-plugin-inline-react-svg/pull/129#issuecomment-2525330068 but since that would change the fundamental idea behind the PR (still emit functions but use assign to merge defaultProps + use a flag at the plugin level to preserve behavior), I'm opening a new one

And to make it clear: we're aware that, at least in NextJS, SSR does not support class components, but we'll consider that a fault of NextJS itself.