Load the Intl.Segmenter and Intl.DurationFormat polyfills only if needed (#2778)

* Load the Intl.Segmenter polyfill only if needed

* Also polyfill Intl.DurationFormat only if needed

* Polyfill Intl.* in tests

* Load the default translations in tests

* Instanciate the Intl.DurationFormat in the component

src/@types/global.d.ts

@@ -6,6 +6,7 @@ Please see LICENSE in the repository root for full details.
 */
 
 import "matrix-js-sdk/src/@types/global";
+import type { DurationFormat as PolyfillDurationFormat } from "@formatjs/intl-durationformat";
 import { Controls } from "../controls";
 
 declare global {
@@ -23,4 +24,9 @@ declare global {
     // Safari only supports this prefixed, so tell the type system about it
     webkitRequestFullscreen: () => void;
   }
+
+  namespace Intl {
+    // Add DurationFormat as part of the Intl namespace because we polyfill it
+    const DurationFormat: typeof PolyfillDurationFormat;
+  }
 }