Add godebugset package to initialize default GODEBUG settings

We have a number of customers that needed to set GODEBUG=tlskyber=0 once we upgraded to Go 1.23 to preserve backwards compatibilty on some TLS servers.

https://tldr.fail/ is a great write-up about why the migration to post-quantum crypto has been breaking some HTTPS servers.

For compatibility reasons, this commit introduces a godebugset package that will make it possible to disable the post-quantum crypto by default.

Relates to #74 (closed)