Fixes BHV-14524 and ENYO-247

## Issue
Tooltips can linger if the focus is programmatically changed or via 5-way from disabled activators

## Fix
Adds a singleton tooltip observer that is notified when a tooltip is display or spotlight focus changes and requests the currently displayed tooltip (if any) be hidden

## Notes
This reverts #1609 with an alternate solution

Enyo-DCO-1.1-Signed-off-by: Ryan Duffy <ryan.duffy@lge.com>
@ryanjduffy Is this what you wanted to use? enyo.singleton() in oop.js