Add tests for importing types from .d.ts with explicit extension (#53890)

tests/cases/conformance/moduleResolution/allowImportingTypesDtsExtension.ts

@@ -0,0 +1,19 @@
+// @allowImportingTsExtensions: true,false
+// @noEmit: true
+// @moduleResolution: classic,node10,node16,nodenext
+// @noTypesAndSymbols: true
+
+// @Filename: /types.d.ts
+export declare type User = {
+    name: string;
+}
+
+// @Filename: /a.ts
+import type { User } from "./types.d.ts";
+export type { User } from "./types.d.ts";
+
+export const user: User = { name: "John" };
+
+export function getUser(): import("./types.d.ts").User {
+    return user;
+}