Support SSL Keylog generation for TLS connections

Particularly in the case of debugging TLS-specific backup issues, it's nice to be able to load a packet dump into Wireshark/ssldump and have it be able to show both the TLS handshake and the application data transferred thereafter. There's a standardized format that OpenSSL also implements, so we should add support to conditionally enable [SSL_CTX_set_keylog_callback](https://www.openssl.org/docs/man1.1.1/man3/SSL_CTX_set_keylog_callback.html) to generate the session key dump.

Locate the TLS connection setup and its OpenSSL integration, then trace how SSL_CTX is configured before using SSL_CTX_set_keylog_callback. Determine how keylog generation should be conditionally enabled and verify that enabled connections expose handshake and application-data keys in the standardized format while disabled connections do not.

Written by the indexing model from the issue text.