XWIKI-7794: Live search should indicate when there are no results
* Added xwiki:suggest:updated event to know when the suggest widget finishes requesting suggestions from all configured sources.
* Changed "Show all results..." to "Go to search page..." because it doesn't make sense to display "Show all results..." when the "No results!" message displayed. Also, "Show all results" message was misleading because it was only taking the user to the search page and the search page can have different results than the ones displayed by the live search (as the live search sources perform specific search queries).