Allow specifying text for font families

[nandi95]

With google fonts you can specify which characters you need and by that reducing the size. This is already possible with the module google-fonts but I'm not seeing an option in this module. Be aware there's a issue/PR currently on the google fonts repo regarding the text option per font family https://github.com/nuxt-modules/google-fonts/issues/106

[danielroe]

This should be possible as a provider-specific override. Probably needs to be integrated somehow with subset support.