Change running apps section to use GroupTask instead of AppInfo

- No longer bind All Apps to TaskbarRecentsController, and register
  RecentsModel.RecentTasksChangedListener instead
- The source of truth for "running tasks" in Desktop mode is the
  DesktopTask#tasks list itself, instead of
  RecentsModel.RunningTasksListener (which is no longer used)
- Added TaskInfo.TaskKey#isVisible to distinguish minimized running apps
- Next CL will hook up the UI for Recent/Running tasks that are
  not part of the Hotseat.

Flag: com.android.launcher3.enable_recents_in_taskbar
Test: TaskbarRecentAppsControllerTest
Fixes: 335398876
Bug: 315354060
Change-Id: I1313f97a791c5c0c1db7443a5d4f1d5bc761981f