Support import fix for missing namespace as well

Author: zhengbli

src/services/codefixes/importFixes.ts

@@ -114,6 +114,7 @@ namespace ts.codefix {
     registerCodeFix({
         errorCodes: [
             Diagnostics.Cannot_find_name_0.code,
+            Diagnostics.Cannot_find_namespace_0.code,
             Diagnostics._0_refers_to_a_UMD_global_but_the_current_file_is_a_module_Consider_adding_an_import_instead.code
         ],
         getCodeActions: (context: CodeFixContext) => {

tests/cases/fourslash/importNameCodeFixNewImportFile3.ts

@@ -0,0 +1,15 @@
+/// <reference path="fourslash.ts" />
+
+//// [|let t: XXX/*0*/.I;|]
+
+// @Filename: ./module.ts
+//// export module XXX {
+////    export interface I {
+////    }
+//// }
+
+verify.importFixAtPosition([
+`import { XXX } from "./module";
+
+let t: XXX.I;`
+]);