Add type exports for FirebaseFunctionsType in admin functions index

Author: stevenkellner

src/admin/functions/index.ts

@@ -4,3 +4,4 @@ export * from './FirebaseRequest';
 export * from './firebaseFunctions';
 export * from './catchErrorToResult';
 export * from './verifyMacTag';
+export type * from './FirebaseFunctionsType';