Add stub file for PiecingItTogether exercise

Author: zamora-carlos

exercises/practice/piecing-it-together/src/main/java/PiecingItTogether.java

@@ -0,0 +1,5 @@
+public class PiecingItTogether {
+    public PartialJigsawInformation getCompleteInformation(PartialJigsawInformation input) {
+        throw new UnsupportedOperationException("Delete this statement and write your own implementation.");
+    }
+}