Extraction Engine: Forbid extraction of non-singleton qualifiers

#KT-8297 Fixed

idea/testData/refactoring/extractFunction/basic/enumQualifier.kt

@@ -0,0 +1,7 @@
+enum class E {
+    A, B, C
+}
+
+fun bar() {
+    val t = <selection>E</selection>.A
+}