Add DPIUtil method to get device zoom for original autoscale value

The autoscale value may be adapted during runtime, either via explicit
methods in DPIUtil or by rewriting the system property. In order to be
able to calculate the device zooom for a different autoscale value, such
as the initial one, this change adds an according method.

Author: akoch-yatta

bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/internal/DPIUtil.java

@@ -597,6 +597,10 @@ public static int getDeviceZoom() {
 	return deviceZoom;
 }
 
+public static int getDeviceZoom(String autoScaleProperty) {
+	return getZoomForAutoscaleProperty(nativeDeviceZoom, autoScaleProperty);
+}
+
 public static void setDeviceZoom (int nativeDeviceZoom) {
 	DPIUtil.nativeDeviceZoom = nativeDeviceZoom;
 	int deviceZoom = getZoomForAutoscaleProperty (nativeDeviceZoom);