[FIR] Check standalone companion object qualifiers are visible

compiler/testData/diagnostics/tests/classObjects/ClassObjectVisibility.fir.kt

@@ -3,9 +3,10 @@ package foo
 fun test() {
   A.d
   A.Companion.<!INVISIBLE_REFERENCE!>f<!>
-  B.D
-  CCC
+  B.<!INVISIBLE_REFERENCE!>D<!>
+  <!INVISIBLE_REFERENCE!>CCC<!>
   CCC.<!INVISIBLE_REFERENCE!>classObjectVar<!>
+  E.F.G
 }
 
 class A() {
@@ -28,3 +29,10 @@ class CCC() {
     val classObjectVar = 3
   }
 }
+
+class E {
+    class F {
+        companion object G
+    }
+    private companion object
+}