Support the discovery of declarative test suites introduced with JUnit 5.8.0-M1

package org.junit.platform.suite;

@Suite
@SelectClasses({
        XTest.class,
        YTest.class,
        ZTest.class
})
class SelectClassesTest {
} 

   SummaryGeneratingListener listener = new SummaryGeneratingListener();
        Launcher launcher = LauncherFactory.create();
        LauncherDiscoveryRequest request = LauncherDiscoveryRequestBuilder.request()
                .selectors(
                        DiscoverySelectors.selectClass(XTest.class),
                        DiscoverySelectors.selectClass(YTest.class),
                        DiscoverySelectors.selectClass(ZTest.class)
                )
                .build();
        launcher.execute(request, listener);
        // get the test execution summary from the given listener