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

idea/testData/quickfix/modifiers/visibilityModiferParameter.kt.after

@@ -0,0 +1,9 @@
+// "Change visibility modifier" "true"
+trait ParseResult<out T> {
+    public val success : Boolean
+    public val value : T
+}
+
+class Success<T>(<caret>public override val value : T) : ParseResult<T> {
+    public override val success : Boolean = true
+}