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

idea/testData/quickfix/changeSignature/notAvailableForSynthesized.kt

@@ -0,0 +1,8 @@
+// "class org.jetbrains.kotlin.idea.quickfix.AddFunctionParametersFix" "false"
+//ERROR: Too many arguments for internal final fun component1(): kotlin.Int defined in Data
+
+data class Data(val i: Int) {}
+
+fun usage(d: Data) {
+    d.component1(<caret>2)
+}