Add "new conversation" composer for direct messages

ts/util/isConversationUnread.ts

@@ -0,0 +1,13 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { isNumber } from 'lodash';
+
+export const isConversationUnread = ({
+  markedUnread,
+  unreadCount,
+}: Readonly<{
+  unreadCount?: number;
+  markedUnread?: boolean;
+}>): boolean =>
+  Boolean(markedUnread || (isNumber(unreadCount) && unreadCount > 0));