Create tooltip for notifying auto-adding the font scaling tile

1. Add string for the content of tooltip.
2. Show the tooltip if needed: the tooltip will only be shown once when users change the font size from the Settings page for the first time.
3. Since the layout shown on the screen will be recreated after font size changes, we need to save the state of the tooltip popup window to check if we need to reshow it in displayPreference.

Bug: 269679768
Test: Manually - attach videos to the bug
Test: make RunSettingsRoboTests ROBOTEST_FILTER=PreviewSizeSeekBarControllerTest
Change-Id: I1b6c5fdbd74c7a868cf42bd21d2cdb1052c0bbe6