Storage service: save new AccountRecord fields to disk

ts/util/phoneNumberSharingMode.ts

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+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { makeEnumParser } from './enum';
+
+// These strings are saved to disk, so be careful when changing them.
+export enum PhoneNumberSharingMode {
+  Everybody = 'Everybody',
+  ContactsOnly = 'ContactsOnly',
+  Nobody = 'Nobody',
+}
+
+export const parsePhoneNumberSharingMode = makeEnumParser(
+  PhoneNumberSharingMode,
+  PhoneNumberSharingMode.Everybody
+);