Add stubs for OpenSSL.SSL

[ohemorange]

Certbot is working on using mypy in our development process! We rely on OpenSSL.crypto and OpenSSL.SSL, and I only see stubs for the former. It would be great to have them for the latter as well.

[gvanrossum]

Can you take a stab at contributing these yourself?

[ohemorange]

Possibly!

[srittau]

We are closing all third-party stub requests issues without recent activity. We still welcome pull requests that add these to typeshed, although distributing the stubs with the the third-party package itself is preferable.