Add a button to the accessibility button tutorial dialog that links directly to the settings page.

When the accessibility button appears, some users don't know how to
control it. Add a button to the tutorial dialog that links directly to
the settings page to help users get more information.

Bug: 183977141
Test: make RunSettingsRoboTests ROBOTEST_FILTER=AccessibilityGestureNavigationTutorialTest
Change-Id: I08d7e5b0771b6bf99f7753ccbcf2e7400227ddc5