Big change in quickfix tests: no stupid test data format with "before" and "after" file prefixes

idea/testData/quickfix/createFromUsage/createClass/referenceExpression/classByNestedQualifier.kt

@@ -0,0 +1,9 @@
+// "Create class 'B'" "true"
+// ERROR: Unresolved reference: C
+package p
+
+fun foo() = A.<caret>B.C
+
+class A {
+
+}