FIR: implement diagnostics for qualifier as stand-alone expression case

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

@@ -36,7 +36,7 @@ val a = A.x
 val c = B.<!UNRESOLVED_REFERENCE!>x<!>
 val d = b.<!UNRESOLVED_REFERENCE!>x<!>
 
-val s = System  // error
+val s = <!NO_COMPANION_OBJECT!>System<!>  // error
 fun test() {
   System.out.println()
   java.lang.System.out.println()

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

@@ -33,7 +33,7 @@ fun f() {
     A().Inner()
     A.Companion.<!UNRESOLVED_REFERENCE!>Nested<!>
     A.Companion.<!UNRESOLVED_REFERENCE!>Inner<!>
-    A.Inner
+    A.<!NO_COMPANION_OBJECT!>Inner<!>
     A.Companion.c
     A.Companion.Obj2
     A.Companion.Obj2.c