web: fix ReferenceError after React Router v7 migration

After migrating to React Router v7, the test suite fails with the
following error:

> ReferenceError: TextEncoder is not defined

This appears to be due to an unimplemented TextEncoder in jsdom. To
resolve this, we follow the same workaround as React Router, as outlined
in remix-run/react-router#12363 (comment)

Author: dgdavid

web/src/setupTests.ts

@@ -3,3 +3,11 @@
 // expect(element).toHaveTextContent(/react/i)
 // learn more: https://github.com/testing-library/jest-dom
 import "@testing-library/jest-dom";
+import { TextDecoder, TextEncoder } from "util";
+
+globalThis.IS_REACT_ACT_ENVIRONMENT = true;
+
+if (!globalThis.TextEncoder || !globalThis.TextDecoder) {
+  globalThis.TextEncoder = TextEncoder;
+  globalThis.TextDecoder = TextDecoder;
+}