Reduce visibility of test classes in Win32 fragment

Some unit test classes in the Win32 fragment are declared as public.
This is unnecessary and may lead to them being erroneously being
considered in the API baseline.

Author: HeikoKlare

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/widgets/CoordinateSystemMapperTests.java

@@ -26,7 +26,7 @@
 import org.junit.jupiter.params.provider.*;
 
 @TestInstance(TestInstance.Lifecycle.PER_CLASS)
-public class CoordinateSystemMapperTests {
+class CoordinateSystemMapperTests {
 
 	Supplier<Monitor[]> getMonitorConsumer;
 	Monitor[] monitors;

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/widgets/DisplayWin32Test.java

@@ -9,7 +9,7 @@
 
 @ExtendWith(PlatformSpecificExecutionExtension.class)
 @ExtendWith(ResetMonitorSpecificScalingExtension.class)
-public class DisplayWin32Test {
+class DisplayWin32Test {
 
 	@Test
 	public void monitorSpecificScaling_activate() {