Support for new double colon expressions in type checker

Despite the fact that the LHS of a double colon expression is now KtExpression
instead of KtUserType, we must still consider it a type for callable references
to work. Extract and reuse relevant parts of QualifiedExpressionResolver and
TypeResolver to support this behavior

compiler/testData/diagnostics/tests/classLiteral/nonClassesOnLHS.kt

@@ -3,7 +3,7 @@
 class A
 
 val a1 = <!CLASS_LITERAL_LHS_NOT_A_CLASS!>A?::class<!>
-val a2 = <!CLASS_LITERAL_LHS_NOT_A_CLASS!>A?<!REDUNDANT_NULLABLE!>?<!>::class<!>
+val a2 = <!CLASS_LITERAL_LHS_NOT_A_CLASS!>A??::class<!>
 
 val l1 = <!CLASS_LITERAL_LHS_NOT_A_CLASS!>List<String>?::class<!>
 val l2 = <!CLASS_LITERAL_LHS_NOT_A_CLASS!>List?::class<!>