Fix for KT-7421: Unable to inherit from inner class

Fix for KT-6708: Compiler Error when extending open inner class: "java.lang.RuntimeException: Error generating primary constructor of class InnerB with kind IMPLEMENTATION"

  #KT-7421 Fixed
  #KT-6708 Fixed

compiler/testData/codegen/boxWithJava/innerClass/JavaClass.java

@@ -0,0 +1,7 @@
+public abstract class JavaClass {
+    public abstract InnerClass onCreateInner();
+
+    public class InnerClass {
+
+    }
+}