`aria-haspopup` use requires the use of an ARIA `menu`, `listbox`, `tree`, `grid` or `dialog` (see https://www.w3.org/TR/wai-aria-1.1/#aria-haspopup)

in our use (as generic disclosure widgets), it's incorrect and sets up the wrong assumption/behavior from assistive technologies.

in future, we likely want to change our dropdowns to essentially be like a `dialog` - move focus to it when opened, possibly make it modal so focus is maintained inside it and the rest of the page
is hidden/inert.

but for now, removing the incorrect attribute is probably the quickest, most immediate fix.

* Improve code coverage for our Button plugin

* improve coverage for our Alert plugin

* test tooltip update method

* test update and dispose for dropdown

* increase code coverage requirements

* Dropdown - Allow to disable Popper.js style

* Update dropdown.js

* Update dropdown.html

* copy changes

* Close dropdown menu when focusing an outside element
* Update unit test to new markup

Fixes #16828
Closes #16865

as role="menu" is a very specific (and strict) ARIA pattern for
desktop-like application menus, and our dropdowns are often used
as pure navigation dropdowns, this change abandons ARIA menus for
a more open-ended and light-weight approach
(see http://heydonworks.com/practical_aria_examples/#submenus and
http://www.w3.org/WAI/tutorials/menus/flyout/#improve-screen-reader-support-using-wai-aria)
note that in dropdown.js, switched to now target ``.dropdown-menu``
instead of ``role["menu"]`` - this also prevents bootstrap scripts
from "bleeding" into non-bootstrap components on the same page.
also removed the ``role=["listbox"]`` part, which appears to be
vestigial/unused (only place in bootstrap that uses that
role are carousels, and their key handling is done separately)

Closes #16073 by merging it

To ensure that we don't accidentally use any of the aliases.
This should prevent any future regressions from #12761.
Also updates the test suite since it now can't use these aliases either.

[Fixes #15953] Implement `assert.expect` in each unit test

Refs #15893

Fixes #15147.
Closes #15520 by merging it.

Redo of #15876

[skip validator]