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/PackageVsClass2.kt

@@ -0,0 +1,15 @@
+// MODULE: m1
+// FILE: a.kt
+package a
+
+class b {
+    fun a_b() {}
+}
+
+// MODULE: m2(m1)
+// FILE: b.kt
+package test
+
+class a
+
+val x = a.<!UNRESOLVED_REFERENCE!>b<!>()