menubar: unit test: rm exercise of private method
menubar test: rm duplicating test
menubar: refactor _create

Remove initialization method:

`_initializeMenubarsBoundElement()`

Rewrite `_initializeWidget()` to include
the work of `_initializeMenubarsBoundElement()`
and the former `this._initializeWidget();`

ALSO: Remove auxiliary non-standard-style
functions:

* `_deactivateMenusParentButton`
* `_disableTabIndexOnFirstMenuItem`
* `_reenableTabIndexOnFirstMenuItem`

ALSO: Remove un-used method: `_closeOpenMenu`
menubar: refactor _create sub-routine: _initializeMenuItems

_create identifies menuItems and then initializes
them.  

ALSO: rm non-standard-style methods: 

`_determineSubmenuStatus`
`_styleMenuItem`
`_initializeSubMenu`
menubar: refactor _create sub-routine: _initializeItems

At this point _create has initialized the
menubar widget and the top level (usually, `li`s)
that define the menubar.

We now want to step through the "actuators"
contained in the menuItems(typically a
`button` or an `a`).

We use an `$.each` here because we need to be
able to apply different behavior wrt the menus
based on whether or not the parent menuItem has
discerned whether it has a subMenu or not.  That
is, we need different behavior if it's a
sub-menu-less menuItem versus a menuItem that
actuates an arbitrary depth sub-menu set.

ALSO:  get rid of non-standard-style helper methods

* `this._applyDOMPropertiesOnItem`
* `this.__applyMouseAndKeyboardBehaviorForMenuItem`
* `this.__applyMouseBehaviorForSubmenuHavingMenuItem`
* `this.__applyKeyboardBehaviorForSubmenuHavingMenuItem`
* `_findNextFocusableTarget`
Remove developer note comment
Extract method, per TODO
Ensure destroy cleans up state on menuItems
use jquery tabs and style