Prohibit accessing nested classes/objects of class object using class literal

The fqname of class should be clear from code
Example: can't shorten A.Default.B.Default.C to A.B.C
Also fixes problem when nested class of enum class could be accessed via enum entry

compiler/testData/diagnostics/tests/classObjects/InnerClassAccessThroughClassObject.kt

@@ -0,0 +1,51 @@
+package a
+
+class A {
+    class Nested
+    inner class Inner
+
+
+    class object {
+
+        class Nested2
+
+        val c: Int = 1
+
+        object Obj2 {
+            val c: Int = 1
+        }
+    }
+
+    object Obj
+}
+
+object O {
+    class A
+
+    object O
+}
+
+fun f() {
+    A.c
+    A.hashCode()
+    A().<!NO_CLASS_OBJECT, NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>Nested<!>
+    A.Nested()
+    A().Inner()
+    A.Default.<!UNRESOLVED_REFERENCE!>Nested<!>
+    A.Default.<!UNRESOLVED_REFERENCE!>Inner<!>
+    A.<!UNRESOLVED_REFERENCE!>Inner<!>
+    A.Default.c
+    A.Default.Obj2
+    A.Default.Obj2.c
+
+    A.Default.Nested2()
+    A.Default.c
+    A.Obj
+    A.Default.Obj2
+    A.<!UNRESOLVED_REFERENCE!>Obj2<!>
+    A.<!UNRESOLVED_REFERENCE!>Obj2<!>.<!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>c<!>
+    A.<!UNRESOLVED_REFERENCE!>Nested2<!>
+
+    O.O
+    O.A()
+}