[Request] allow "get everything" option on /css2

Hi. I'm developing a live CSS browser feature ([video](https://polypane.app/blogs/polypane-2-1/livecss.mp4)) where people can use any Google Font in their CSS and I dynamically load the font for them. I would like to move to the `/css2` api and provide support for variable fonts, but I'm encountering issues.

If I request just the font, I don't think I get enough (e.g. https://fonts.googleapis.com/css2?family=Changa&display=swap) so, I want to request the full range of options. Theoretically I should be able to get this with `:ital,wght@0,100..900;1,100..900`, but for Changa for example that range is invalid (Changa only has 200..800) and this results in an error page.

Rather than getting an error page back, I'd like to get back just everything that's available. Either by default where the API endpoint is more forgiving, or with an additional query param.