Fix TaskInfo#requestedVisibleTypes update conditions

1) Force a task info changed dispatch whenever the window's requested
   visible types change, otherwise WMShell window decorations might show
   the wrong UI if it's out of sync with the true window state.
2) Obtain the requested types from top app window *excluding* the
   starting window

Flag: com.android.window.flags.enable_fully_immersive_in_desktop
Fix: 375509830
Test: open Candy Crush in desktop, immersive icon is shown on launch
without having to move the window first to trigger an update

Change-Id: I23eca5da60fcb5f9b167c64be7b8aaa94139a3ba