fix(types): add i18n types to gip context

Author: rokinsky

packages/next/next-server/lib/utils.ts

@@ -135,6 +135,18 @@ export interface NextPageContext {
    * `String` of the actual path including query.
    */
   asPath?: string
+  /**
+   * The currently active locale
+   */
+  locale?: string
+  /**
+   * All configured locales
+   */
+  locales?: string[]
+  /**
+   * The configured default locale
+   */
+  defaultLocale?: string
   /**
    * `Component` the tree of the App to use if needing to render separately
    */