Add TLS callbacks for debug and error logging.
Add TLS callbacks for debug and error logging.

Not currently called but leaves us the opening to use them in the future
without breaking ABI.

webmaster128/botan,Rohde-Schwarz-Cybersecurity/botan,webmaster128/botan,randombit/botan,randombit/botan,webmaster128/botan,Rohde-Schwarz-Cybersecurity/botan,webmaster128/botan,randombit/botan,webmaster128/botan,Rohde-Schwarz-Cybersecurity/botan,randombit/botan,randombit/botan,Rohde-Schwarz-Cybersecurity/botan,Rohde-Schwarz-Cybersecurity/botan,Rohde-Schwarz-Cybersecurity/botan