Consider adding Support for SSLKEYLOGFILE

[jplummer01]

Please consider adding support the SSLKEYLOGFILE as documented in this Issue seanmonstar/reqwest#1016

This is very useful for using tools like Wireshark to debug the connection between developer and the backend services such as OpenAI to see exactly the payload on the wire.

Additional Info is also here
https://blog.didierstevens.com/2020/12/28/decrypting-tls-streams-with-wireshark-part-2/

[jeremychone]

Ok, I will look at it when more time.
First, I will probably add tracing, but won't probably trace the payloads.