Variables
Const DROP_DOWN
DROP_DOWN: "ww-drop-down-menu" = "ww-drop-down-menu"
Const DROP_DOWN_CONTENT
DROP_DOWN_CONTENT: "ww-drop-down__content" = "ww-drop-down__content"
Const DROP_DOWN_TOGGLE
DROP_DOWN_TOGGLE: "ww-drop-down-menu__toggle" = "ww-drop-down-menu__toggle"
ButtonTemplate provides the template for rendering the button part.