Modify Accessibility Setting UI for timeout feature

Using single timeout setting page instead of current two timeout pages
to keep the user experience simple and reduce confusion.

Current timeout page & API:
'Time to take action'
    --  Settings.Secure.ACCESSIBILITY_INTERACTIVE_UI_TIMEOUT_MS
'Time to read'
    --  Settings.Secure.ACCESSIBILITY_NON_INTERACTIVE_UI_TIMEOUT_MS

New timeout page & API:
'Time to take action(Accessibility timeout)'
    --  Settings.Secure.ACCESSIBILITY_INTERACTIVE_UI_TIMEOUT_MS
    --  Settings.Secure.ACCESSIBILITY_NON_INTERACTIVE_UI_TIMEOUT_MS

Bug: 132247225
Test: make RunSettingsRoboTests -j ROBOTEST_FILTER=AccessibilityTimeoutControllerTest
Test: make RunSettingsRoboTests -j ROBOTEST_FILTER=AccessibilitySettingsTest
Change-Id: I0b69682425324d3b1e0ff3f7b6e2c299b60cd215