jvm-abi-gen: Add tests for uses of private Kotlin classes from Java

plugins/jvm-abi-gen/testData/compile/privateClassesFromJavaLib/lib/J.java

@@ -0,0 +1,7 @@
+package lib;
+
+public class J {
+    public static String result() {
+        return new A().result();
+    }
+}