j2k: flatten test cases and testData directory structure

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

j2k/testData/multiFile/GetterAndSetterUsages/1.java

@@ -0,0 +1,19 @@
+public class AAA {
+    private int x = 42;
+
+    public int getX() {
+        return x;
+    }
+
+    public void setX(int x) {
+        this.x = x;
+    }
+
+    public void foo() {
+        setX(getX() + 1);
+    }
+
+    public void bar(B b) {
+        System.out.println(b.getYY());
+    }
+}