Improving Hovercards' settings dialog to fulfill design specification.
Also fixing HTML structure by removing invalid `radiogroup` element and
adding missing `</div>` element, fixing related QUnit test.
Changes:
* Add close icon instead of using text
* Style header as a table for alignment
* Remove redundant "OK" button and have it replace "Save" instead
* Update text of "OK" button to "Done"
* Fix description for translation of "Done" button
* Fix qunit and selenium tests
* Remove unnecessary markup and less
* Add mediawiki-ui-button and mediawiki-ui-icon dependencies
* Shrink dialog width some per design spec
* Fix dialog horizontal position calculation to remove hard-coded value
Bug: T138612
Change-Id: I7395e3438836149becdd576942bdaf6f21b4163f
