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

idea/testData/completion/handlers/ClassFromClassObjectInPackage.kt

@@ -7,5 +7,5 @@ class Test {
 }
 
 fun test() {
-    a.Test.S<caret>
+    a.Test.Default.S<caret>
 }