Created by: MattyQ
Update to tooltip.js and tests to add an aria-label attribute that contains the original title of the element, but only if the element doesn't have an existing, valid aria-label attribute.
This is to address cases where screen readers are not capturing the aria-describedby attribute that is added when the tooltip is triggered. This should also avoid a label not being read because of any race conditions between the screen reader and the appearance of the tooltip.
In the case the aria-describedby attribute is added as intended, it overrides the aria-label, so there should be no collision between the two methods of labeling. The aria-label attribute is added conditionally to avoid conflicting with other ways someone might already be adding aria-label attributes to their elements.