Refactor languageHandler to avoid import cycles (#33948)

* Refactor languageHandler to avoid import cycles

Also move its tests to vitest

* Small refactor

* Iterate

* Iterate

apps/web/test/unit-tests/components/views/rooms/RoomKnocksBar-test.tsx

@@ -32,7 +32,7 @@ import {
     getMockClientWithEventEmitter,
     mockClientMethodsUser,
 } from "../../../../test-utils";
-import * as languageHandler from "../../../../../src/languageHandler";
+import * as languageSettings from "../../../../../src/i18n/settings";
 
 describe("RoomKnocksBar", () => {
     const userId = "@alice:example.org";
@@ -132,7 +132,7 @@ describe("RoomKnocksBar", () => {
             jest.spyOn(state, "hasSufficientPowerLevelFor").mockReturnValue(true);
             jest.spyOn(Modal, "createDialog");
             jest.spyOn(dis, "dispatch");
-            jest.spyOn(languageHandler, "getUserLanguage").mockReturnValue("en-GB");
+            jest.spyOn(languageSettings, "getUserLanguage").mockReturnValue("en-GB");
         });
 
         it("does not render if user can neither approve nor deny", () => {