Move getMessageById next to getMessagesById

ts/messages/getMessageById.ts

@@ -0,0 +1,33 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import * as log from '../logging/log';
+import type { MessageModel } from '../models/messages';
+import * as Errors from '../types/errors';
+
+export async function getMessageById(
+  messageId: string
+): Promise<MessageModel | undefined> {
+  let message = window.MessageController.getById(messageId);
+  if (message) {
+    return message;
+  }
+
+  try {
+    message = await window.Signal.Data.getMessageById(messageId, {
+      Message: window.Whisper.Message,
+    });
+  } catch (err: unknown) {
+    log.error(
+      `failed to load message with id ${messageId} ` +
+        `due to error ${Errors.toLogFormat(err)}`
+    );
+  }
+
+  if (!message) {
+    return undefined;
+  }
+
+  message = window.MessageController.register(message.id, message);
+  return message;
+}