Add @font-face that combines normal and italic fonts

[quiple]

Currently, if you want to use both normal and italic fonts in your project using this package, you must manually specify each font family.

html {
  font-family: 'Geist-Variable';
}
i {
  font-family: 'Geist-VariableItalic';
}

Resolves the issue by adding a CSS file that merges font families into one.

The exports in package.json are redefined as follows:

• non.geist (added)
• non.geist -> non.geist/sans
• non.geist/italic
• non.geist/m (added)
• non.geist/mono
• non.geist/mono-italic

If there is a better suffix, please update.

Thanks for this package!