tls: expose keylog event on TLSSocket

Exposes SSL_CTX_set_keylog_callback in the form of a `keylog` event
that is emitted on clients and servers. This enables easy debugging
of TLS connections with i.e. Wireshark, which is a long-requested
feature.

PR-URL: https://github.com/nodejs/node/pull/27654
Refs: https://github.com/nodejs/node/issues/2363


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>