bpo-32604: PEP 554 for use in test suite (GH-19985)

* PEP 554 for use in test suite

* 📜🤖 Added by blurb_it.

* Fix space

* Add doc to doc tree

* Move to modules doc tree

* Fix suspicious doc errors

* Fix test__all

* Docs docs docs

* Support isolated and fix wait

* Fix white space

* Remove undefined from __all__

* Fix recv and add exceptions

* Remove unused exceptions, fix pep 8 formatting errors and fix _NOT_SET in recv_nowait()

Co-authored-by: nanjekyejoannah <joannah.nanjekye@ibm.com>
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>