j2k: flatten test cases and testData directory structure

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

j2k/testData/fileOrElement/newClassExpression/genericClassInvocation.kt

@@ -0,0 +1,7 @@
+import java.util.ArrayList
+
+class User {
+    fun main() {
+        val list = ArrayList<String>()
+    }
+}