Implementing the TODO in pingora-core rustls listener to avoid panics by returning a Result

[omavashia2005]

Fixes #927

All tests pass with cargo test -p pingora-core

[drcaramelsyrup]

Seems like this can still panic here vs. returning the Err?

[drcaramelsyrup]

Likewise, if we're going to change the API here anyhow, we should translate these panics into Errs as well.

[omavashia2005]

Right, I was waiting for some feedback before changing this. I wanted to confirm whether those panics were intentional or if they should be changed as well before updating this and a few other panic!/unwrap() calls. Commits coming soon. Thanks for the feedback!

[omavashia2005]

Working on these still - mb for pushing - these currently fail with cargo build --features s2n and cargo build --features rustls

[omavashia2005]

this should be working now since cargo build --features s2n and cargo build --features rustls succeed.

[omavashia2005]

Hey! Just following up...let me know if I need to make any further changes :)

Thanks!