Add support for ACI safety numbers behind a feature flag

ts/components/SafetyNumberNotReady.tsx

@@ -0,0 +1,42 @@
+// Copyright 2023 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import React from 'react';
+
+import { Button, ButtonVariant } from './Button';
+import { Modal } from './Modal';
+import { Intl } from './Intl';
+import { openLinkInWebBrowser } from '../util/openLinkInWebBrowser';
+import type { LocalizerType } from '../types/Util';
+import { SAFETY_NUMBER_MIGRATION_URL } from '../types/support';
+
+export type PropsType = {
+  i18n: LocalizerType;
+  onClose: () => void;
+};
+
+function onLearnMore() {
+  openLinkInWebBrowser(SAFETY_NUMBER_MIGRATION_URL);
+}
+
+export function SafetyNumberNotReady({
+  i18n,
+  onClose,
+}: PropsType): JSX.Element | null {
+  return (
+    <div className="module-SafetyNumberNotReady">
+      <div>
+        <Intl i18n={i18n} id="icu:SafetyNumberNotReady__body" />
+      </div>
+
+      <Modal.ButtonFooter>
+        <Button onClick={onLearnMore} variant={ButtonVariant.Secondary}>
+          <Intl i18n={i18n} id="icu:SafetyNumberNotReady__learn-more" />
+        </Button>
+        <Button onClick={onClose} variant={ButtonVariant.Secondary}>
+          <Intl i18n={i18n} id="icu:ok" />
+        </Button>
+      </Modal.ButtonFooter>
+    </div>
+  );
+}