support icu messageformat for translations

ts/types/I18N.ts

@@ -9,6 +9,7 @@ export type { LocalizerType } from './Util';
 
 type SmartlingConfigType = {
   placeholder_format_custom: string;
+  string_format_paths?: string;
   translate_paths: Array<{
     key: string;
     path: string;
@@ -16,15 +17,10 @@ type SmartlingConfigType = {
   }>;
 };
 
-type LocaleMessageType = {
-  message: string;
+export type LocaleMessageType = {
+  message?: string;
+  messageformat?: string;
   description?: string;
-  placeholders?: {
-    [name: string]: {
-      content: string;
-      example: string;
-    };
-  };
 };
 
 export type LocaleMessagesType = {

ts/types/Util.ts

@@ -1,6 +1,7 @@
 // Copyright 2018-2021 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
+import type { IntlShape } from 'react-intl';
 import type { UUIDStringType } from './UUID';
 
 export type BodyRangeType = {
@@ -31,6 +32,8 @@ export type ReplacementValuesType =
 
 export type LocalizerType = {
   (key: string, values?: ReplacementValuesType): string;
+  getIntl(): IntlShape;
+  isLegacyFormat(key: string): boolean;
   getLocale(): string;
 };