IA updates - Group all menu related components together

[mcarrano]

To make it easier to find and choose between menu components including dropdowns and selects of various types, use tertiary navigation to group all existing form components together.

Category name: TBD
Components:

• Dropdown

• Menu

• Menu toggle

• Select

• Composable menu demos (need a tag to identify demos vs components) - break up to include all demos at top level.
  Type-ahead select
  Menu with actions
  Drilldown
  Tree menu
  Fly-out
  Application launcher
  Context selector

[mcarrano]

Close in favor of #3471