Add simple `Reader` and `Writer` protocols

[srittau]

Feature or enhancement

Proposal:

See the discourse thread for the rationale.

Has this already been discussed elsewhere?

I have already discussed this feature proposal on Discourse

Links to previous discussion of this feature:

https://discuss.python.org/t/simple-reader-and-writer-protocols/61510

Linked PRs

• gh-127647: Add typing.Reader and Writer protocols #127648