[BAEL-3488] Timer Class (#8769)

* [BAEL-3488] Moving code to core-java where the original article code was located

* [BAEL-3488] Moved original code under timer package

core-java-modules/core-java/src/test/java/com/baeldung/timer/JavaTimerLongRunningUnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung;
+package com.baeldung.timer;
 
 import org.junit.Test;
 import org.slf4j.Logger;