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

idea/testData/quickfix/createFromUsage/createFunction/binaryOperations/plusMissingArgs.kt

@@ -0,0 +1,9 @@
+// "Create function 'plus'" "true"
+
+class A<T>(val n: T) {
+    fun plus(i: Int, s: String): A<T> = throw Exception()
+}
+
+fun test() {
+    val a: A<Int> = A(1) <caret>+ 2
+}