lib: include return types in JSDoc

Add types to @returns JSDoc annotations where the type is missing.

PR-URL: https://github.com/nodejs/node/pull/41130
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

lib/internal/blob.js

@@ -129,7 +129,7 @@ class Blob {
    *   endings? : string,
    *   type? : string,
    * }} [options]
-   * @returns
+   * @constructs {Blob}
    */
   constructor(sources = [], options = {}) {
     emitExperimentalWarning('buffer.Blob');