feat: support undefined locale

Author: json-derulo

projects/angular-ecmascript-intl/src/lib/locale.ts

@@ -1,7 +1,7 @@
-import { InjectionToken } from "@angular/core";
+import {InjectionToken} from "@angular/core";
 
 /**
  * Set the locale(s) for all Intl Pipes. If not specified, the user language specified in the browser will be used. If
  * specified, it needs to be a string with a BCP 47 language tag, or an array of such strings.
  */
-export const INTL_LOCALES = new InjectionToken<string | string[]>('IntlLocales');
+export const INTL_LOCALES = new InjectionToken<string | string[] | undefined>('IntlLocales');