Add support for configuring default font-variation-settings for a font-family

[ngrushkovsky]

I wanted to set default font-variation-settings for the beta version of Inter, which includes Inter Display as an optical size variation axis. However, I discovered that there is no support for this option in the current codebase.

In addition to existing support for font-feature-settings, this pull request adds support for configuring default font-variation-settings for a font-family. This will give users more control over how the fonts are rendered in their projects.

module.exports = {
  theme: {
    fontFamily: {
      sans: [
        'Inter var, sans-serif',
        {
          fontFeatureSettings: '"cv11", "ss01"',
          fontVariationSettings: '"opsz" 32',
        },
      ],
    },
  },
}

I decided not to open a feature request for this change as it may not be significant enough, and I hope that's okay. Thank you for considering this change, and for all the work you've done on this amazing framework! ❤

[adamwathan]

Thanks I think this makes perfect sense to support! Need to prepare a documentation update before merging so will leave this open for now, but plan to merge once I have a chance to update the documentation. Trying to be better about not leaving myself a shit ton of documentation work to do right before a release comes out 😄

[adamwathan]

@RobinMalfait do you mind rebasing and resolving the conflicts here and merging when you get a chance tomorrow? Will just do the documentation sometime before the v3.3 release — just need to make sure this is in the changelog so we don't forget 👍