j2k: flatten test cases and testData directory structure

Move j2k/test/tests -> j2k/tests, j2k/test/testData -> j2k/testData

j2k/testData/fileOrElement/rawGenerics/kt-540.java

@@ -0,0 +1,13 @@
+//file
+package demo;
+
+import java.util.List;
+import java.util.ArrayList;
+
+class Test {
+  void main() {
+    List<String> common = new ArrayList<String>();
+    List raw = new ArrayList<String>();
+    List superRaw = new ArrayList();
+  }
+}