Send/Skip CCS, set legacy record version to 3,3 and echo session ID.
CCS must be ignored while the handshake is running, but not thereafter:
https://tools.ietf.org/html/draft-ietf-tls-tls13-22#section-5
Unconditionally send CCS as server because bogo requires it, even if no
session ID is included in the Client Hello. TLS 1.3 clients MUST ignore
it anyway, so it should not hurt.
Fixes interop with boringssl and openssl and passes bogo.