Implement the map method on readable stream. This starts the alignment
with the tc39-iterator-helpers proposal and adds a `.map` method to
every Node.js readable stream.
Co-Authored-By: Robert Nagy <ronag@icloud.com>
PR-URL: https://github.com/nodejs/node/pull/40815
Reviewed-By: Robert Nagy <ronagy@icloud.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
