Export CallableResponse type in v2/https. (#1665)

Without the change, reference documentations for CallableResponse isn't being correctly generated.

Author: taeold

src/v2/providers/https.ts

@@ -47,7 +47,7 @@ import { SecretParam } from "../../params/types";
 import * as options from "../options";
 import { withInit } from "../../common/onInit";
 
-export { Request, CallableRequest, FunctionsErrorCode, HttpsError };
+export { Request, CallableRequest, CallableResponse, FunctionsErrorCode, HttpsError };
 
 /**
  * Options that can be set on an onRequest HTTPS function.