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/callableReference/packageInLhs.txt

@@ -0,0 +1,9 @@
+package
+
+package foo {
+    public fun test(): kotlin.Unit
+
+    package foo.bar {
+        public fun test(): kotlin.Unit
+    }
+}