Add ratio utility styles and tokens

[marineFabien]

🚀 Styleguide feature request

Description

Regarding Mozaic-freemarker, we need to implement Mozaic image ratios utilities styles and tokens from @mozaic-ds to mozaic-freemarker.

Describe the solution you'd like

These tokens and styles are already available and ready in Mozaic-freemarker socle, and its respect Mozaic guidelines about ratios. That's why it will be better if you move it inside Mozaic.

You can see it here for tokens => https://github.com/adeo/mozaic-freemarker/blob/master/css/_settings-tools/_ratio.scss
You can see it here for utility styles => https://github.com/adeo/mozaic-freemarker/blob/master/css/_utilities/_ratio.scss

Thanks for your answer