Add new component - dropdown - to md-components

Figma-design: https://www.figma.com/design/6BUqOC0xQZz6AggPvI2iSR/Komponenter?m=auto&node-id=15318-2202&t=Qm3Ctp4rNuiQXtay-1

Use Ariakit as basis for the component
https://ariakit.org/components/menu

The component can:

• be used with or without icons for each of the rows
• be used with or without headings
• be used with or without dividers