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

idea/testData/quickfix/migration/lambdaSyntax/lambdaInFunctionArgument.kt.after

@@ -0,0 +1,10 @@
+// "Migrate lambda syntax" "true"
+
+class A
+
+fun foo(a: (Int).(String) -> Int) {
+
+}
+
+
+val a = foo (fun Int.(a: String): Int = 4)