Remove 'inner enum' hack & fix Java inner class resolve

Inner enum was placed into the class object of the outer class. Remove the
hack from frontend, frontend.java & backend. Fix tests

 #KT-1174 In Progress

compiler/testData/javaDescriptorResolver/staticMembers/Enum_non_static.txt

@@ -12,15 +12,15 @@ public final enum class Enum : jet.Enum<test.Enum> {
         public final val C : test.Enum
         public final fun valueOf(/*0*/ value : jet.String) : test.Enum
         public final fun values() : jet.Array<test.Enum>
-        
-        public open class Nested : java.lang.Object {
-            public constructor Nested()
-            public/*package*/ open fun foo() : Unit
-        }
     }
     
     public open inner class Inner : java.lang.Object {
         public constructor Inner()
         public/*package*/ open fun bar() : Unit
     }
+    
+    public open class Nested : java.lang.Object {
+        public constructor Nested()
+        public/*package*/ open fun foo() : Unit
+    }
 }