Problem: When Talkback on, users cannot use double tap or swipe to move focus on the next window.
Solution: Talkback speaks out "double tap to dismiss" to allow dismissing this tooltips.
Bug: 215656141
Test: make RunSettingsRoboTests ROBOTEST_FILTER=AccessibilityQuickSettingsTooltipWindowTest
Change-Id: I8f7066a805ec963f9f0f8fee1b81ad008418c4a6