Add the new migration tooltip for accessibility floating menu.(1/n)

Goal:
If users have been using the accessibility button in android R, after the device is upgraded from android R to S, the system will pop up the tooltip at the first boot to show the information about the Accessibility button was replaced with the floating menu.

Patch Action:
1. Create the tooltip view
2. Create new secure settings  key for migration tooltip

Bug: 175365399
Test: atest AccessibilityFloatingMenuViewTest AccessibilityFloatingMenuTest AccessibilityFloatingMenuTooltipViewTest
Change-Id: I50b792efcbb631778a668e967fd727806a3f3df4