Improvements to the media editor

ts/util/isAciString.ts

@@ -0,0 +1,9 @@
+// Copyright 2023 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import type { AciString } from '../types/ServiceId';
+import { isValidUuid } from './isValidUuid';
+
+export function isAciString(value?: string | null): value is AciString {
+  return isValidUuid(value);
+}