Tabs: Support vertical mode

[benjamincharity]

• Implement vertical mode via an @input layout: 'vertical' | 'horizontal'
  • Default to 'horizontal' layout.
• Content areas should still move horizontally regardless of the layout
• Width of vertical tab should default to spacing(large, 6) (96px)
• All vertical tab heights should match
  • For height: we check height of all tabs and find the tallest; then set the height of all vertical tabs to that height.
• Expose public method that a consumer can call to trigger an update to the tab heights
• Vertical tabs will not make use of the ink bar
• Selected tab is indicated by a white background and left edge colored primary.

Example design:

[benjamincharity]

This has a bespoke implementation within an app. Bumping to backlog until another use-case is defined.