bpo-33734: asyncio/ssl: a bunch of bugfixes (GH-7321) (GH-7396)

* Fix AttributeError (not all SSL exceptions have 'errno' attribute)

* Increase default handshake timeout from 10 to 60 seconds
* Make sure start_tls can be cancelled correctly
* Make sure any error in SSLProtocol gets propagated (instead of just being logged)
(cherry picked from commit 9602643120a509858d0bee4215d7f150e6125468)

Co-authored-by: Yury Selivanov <yury@magic.io>
8 files changed