menubar: Repair TAB order bugs

I believe this fixes tab order.

Regrettably I cannot get the unit test (included
in this commit) which verifies the function of TAB
by use of `simulate` functioning.

The test under investigation is:

"TAB order should be sane mirroring dialog's test "

in `menubar_events.js`.

I'm including it in the PR in hopes that
additional review will present the flaw in my
implementation.  I've tried mirroring the use in
dialog's test suite with no success.

Curiously my use of `simulate` _seems_ right
insofar as my test using it to trigger RIGHT and
LEFT cursor key events _is_ behaving as expected.
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 whitespace style