Add test case for codeFix

tests/cases/fourslash/codeFixUnusedIdentifier_parameter_modifier.ts

@@ -0,0 +1,22 @@
+/// <reference path='fourslash.ts' />
+
+// @noUnusedLocals: true
+// @noUnusedParameters: true
+
+////export class Example {
+////    prop: any;
+////    constructor(private arg: any) {
+////        this.prop = arg;
+////    }
+////}
+
+verify.codeFix({
+    description: "Remove declaration for: 'arg'",
+    newFileContent:
+`export class Example {
+    prop: any;
+    constructor(arg: any) {
+        this.prop = arg;
+    }
+}`,
+});