Hide SAW subwindows

.. when top window is hidden through Window#setHideOverlayWindows

Bug: 318683640
Test: atest CtsWindowManagerDeviceWindow:HideOverlayWindowsTest
Flag: EXEMPT securityfix
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:c37bc9147086f497ac7b1595083836014f524d5f)
Merged-In: If19240f5aec2e048de80d75cbbdc00be47622d7f
Change-Id: If19240f5aec2e048de80d75cbbdc00be47622d7f