Implement a minimal design system for XWiki

Currently, two design systems are implemented on top of the abstract design system API: Vuetify and Shoelace, both in Cristal.
To be able to define reusable components while being aligned with the current look & feel of XWiki, we need to define a dedicated design system for XWiki.

This first iteration will contain UI elements that are in use in Cristal, at the exception of the more complex tree element (XAlert, XAvatar, XBreadcrumb, XBtn, XDialog, XDivider, XImg, XLoad, XMenu, XMenuItem, XMenuLabel, XTab, XTree, XCheckbox, XFileInput, XForm, XSelect, XTextField, XCard, XCol, XContainer, XSearch)