This module is a specialized implementation of [`tokio-native-tls`](https://crates.io/crates/tokio-native-tls) for
OpenSSL so that we can get ALPN support on the server-side.
The code and tests are from [`tokio-native-tls`](https://crates.io/crates/tokio-native-tls) and
[`native-tls`](https://crates.io/crates/native-tls).