UCL: 27 - Divider

[Brookeruu]

• Create new Divider atom
• Adds horizontal and vertical variants
• Adds length variants (name change from 'width')
• Adds thickness variants
• Adds color variants

I don't think we need to add any accessibility attributes for now. From what I read, the aria attribute role="separator" is only used if the separator is focusable or in a menu.