Tabs - nav variant

[kmcfaul]

Add new flag for full nav styling (optionally, also set the component="nav" when this is passed).

[thatblindgeye]

@dlabaj just to add onto the above:

• We should set it up so that when isNav is true in Tabs, the Component should default to a nav element
  • This should be able to be overridden by passing component="div" prop