Refactor education proto into 3 separate protos to allow them to be triggered independently.

* Deprecate existing "education viewed" and "feature used" protos
* Add 3 protos for app handle hint, enter desktop mode hint and exit desktop mode hint for last 'viewed' timestamps
* This is to allow the three tooltips to launch independently based on the conditions of whether the user has viewed and/or used the previous tooltips
* Next CL: trigger next tooltip on user clicking the app handle and entering desktop mode, so we won't need to rely on whether the tooltip was clicked on
* Figma for the three tooltips: https://www.figma.com/design/ofwASs0sC7KsK6VqAkBV3Y/V-%E2%80%A2-Desktop-Windowing-%F0%9F%91%BE%F0%9F%91%BE-Jam-Space?node-id=18349-437720&node-type=frame&t=PntnNQHOHUKUcWdR-0

Bug: 371527084
Change-Id: If7217b207b6291e407e38f28a70b066f5f590efb
Test: atest AppHandleEducationControllerTest
Flag: com.android.window.flags.enable_desktop_windowing_app_handle_education