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

[adamwathan]

This PR adds support for an options object when configuring custom font families where you can specify default font-feature-settings for that font.

Inspired by this discussion: #9034

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

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