Fix Search Dropdown Selection

[garrettmflynn]

This PR fixes the user's ability to select matched elements of the Search list (e.g. global Species metadata on the Subject Metadata page).

Adding an onblur callback on #548 resulted in blocking the usual onclick event since blur events are primary. This is avoided by checking whether the associated target element is one of the list items that the user clicked on, allowing us to skip the onblur callback if this is the case.