Fix microphone permission checking for audio recording

See [#5580][0].

[0]: https://github.com/signalapp/Signal-Desktop/pull/5580

ts/util/requestMicrophonePermissions.ts

@@ -0,0 +1,14 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+export async function requestMicrophonePermissions(): Promise<boolean> {
+  const microphonePermission = await window.getMediaPermissions();
+  if (!microphonePermission) {
+    await window.showCallingPermissionsPopup(false);
+
+    // Check the setting again (from the source of truth).
+    return window.getMediaPermissions();
+  }
+
+  return true;
+}