Add Voice Broadcast labs setting and composer button (#9279)

* Add Voice Broadcast labs setting and composer button

* Implement strict typing

* Extend MessageComposer-test

* Extend tests

* Revert some strict type fixex

* Convert FEATURES to enum; change case

* Use fake timers in MessageComposer-test

test/test-utils/composer.ts

@@ -0,0 +1,33 @@
+/*
+Copyright 2022 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// eslint-disable-next-line deprecate/import
+import { ReactWrapper } from "enzyme";
+import { act } from "react-dom/test-utils";
+
+export const addTextToComposer = (wrapper: ReactWrapper, text: string) => act(() => {
+    // couldn't get input event on contenteditable to work
+    // paste works without illegal private method access
+    const pasteEvent = {
+        clipboardData: {
+            types: [],
+            files: [],
+            getData: type => type === "text/plain" ? text : undefined,
+        },
+    };
+    wrapper.find('[role="textbox"]').simulate('paste', pasteEvent);
+    wrapper.update();
+});