Use correct timestamp for receipts of edited messages

ts/util/getMessageSentTimestampSet.ts

@@ -0,0 +1,17 @@
+// Copyright 2023 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import type { MessageAttributesType } from '../model-types.d';
+
+export function getMessageSentTimestampSet({
+  sent_at: sentAt,
+  editHistory,
+}: Pick<
+  MessageAttributesType,
+  'sent_at' | 'editHistory'
+>): ReadonlySet<number> {
+  return new Set([
+    sentAt,
+    ...(editHistory?.map(({ timestamp }) => timestamp) ?? []),
+  ]);
+}