Add type for RootTagContext

Summary:
This is exported from the RN entrypoint and documented on the RN website, so we should give types for it.

Changelog:
[General][Fixed] - Add type for RootTagContext

Reviewed By: christophpurrer

Differential Revision: D42040806

fbshipit-source-id: cb8cdf557098ddbe33c143b7ab5d80bda7f80a6e

Author: NickGerleman

Libraries/ReactNative/RootTag.d.ts

@@ -0,0 +1,13 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import type * as React from 'react';
+
+export type RootTag = number;
+export const RootTagContext: React.Context<RootTag>;

types/index.d.ts

@@ -126,6 +126,7 @@ export * from '../Libraries/PushNotificationIOS/PushNotificationIOS';
 export * from '../Libraries/ReactNative/AppRegistry';
 export * from '../Libraries/ReactNative/I18nManager';
 export * from '../Libraries/ReactNative/RendererProxy';
+export * from '../Libraries/ReactNative/RootTag';
 export * from '../Libraries/ReactNative/UIManager';
 export * from '../Libraries/ReactNative/requireNativeComponent';
 export * from '../Libraries/Settings/Settings';