Qualifier no longer defers "(nested) class vs package" resolution.

Consider FQN 'a.b.c'.
If 'a' is a classifier in the current scope,
    resolve rest in the corresponding class scope.
Otherwise (if 'a' is a package),
    find the maximum possible prefix 'a.b' resolving to a package,
    resolve rest in the corresponding package scope.

compiler/testData/diagnostics/tests/qualifiedExpression/PackageVsRootClass.kt

@@ -40,5 +40,5 @@ fun test(_ab: a.b) {
     _ab._ab()
 
     val _ab2 = a.b()
-    _ab2.<!UNRESOLVED_REFERENCE!>_ab<!>() // todo
+    _ab2._ab() // todo
 }