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

compiler/fir/analysis-tests/testData/resolve/expresssions/qualifierPriority.kt

@@ -23,7 +23,8 @@ object D {
 val D.E get() = ""
 
 val def = D.E.F // object
-val de = D.E // extension
+// See KT-46409
+val de = D.<!NO_COMPANION_OBJECT!>E<!> // Should be: extension & no error, in fact: qualifier
 
 enum class G {
     H;