Custom Menu Demos - reorganize and clean up demos

[nicolethoen]

Should not be started until the deprecate select PR is merged

• Rename demos so they don’t use word ‘composable’
• Fix flyout and drilldown demos
• Remove the following (which have basically already been moved to new component docs)
  • simple dropdown
  • Simple select
  • Checkbox select
  • Typeahead
  • multitypeahead
  • Dropdown variants
• Convert remaining demos to use new Select or Dropdown (no more popper)
  • use application launcher demo from the custom menus again in Application Launcher docs under React Demo tab
  • use context selector demo from the custom menus again in context selector docs under React Demo tab
  • use options menu demo from the custom menus again in options menu docs under React Demo tab
• Add Favorites demo (should work like the deprecated Select's example, and use the new Select)