Add TYPE_MAGNIFICATION_OVERLAY to InputWindowInfo::isTrustedOverlay()

This fixes a bug where a View with filterTouchesWhenObscured will have
all touches filtered when in magnification accessibility mode. This is
due to magnification being a separate Window over top of the running
Activity. The method onFilterTouchEventForSecurity in View will then
always return false when filterTouchesWhenObscured is enabled on the
View. By adding the magnification Window to the list of Trusted Overlays
we can ensure that touches will work properly with this property enabled.

Change-Id: I07706588a625682d05da5cb19f401139eb08a54c