To better help debugging when things go wrong after radicle-node crashes, RUST_BACKTRACE is registered in the main. According to this StackOverflow answer, this should not affect performance

Registers a panic handler to provide nicer information when the radicle-node panics. This partly inspired by a suggestion from a contributor and provided a link to their approach¹.

Changes:

• Only set RUST_BACKTRACE if it has not been set by the environment already
• Document panic handler

Remove the custom panic handler and use log-panics crate in the logger module instead.

Remove unnecessary error printing.

Remove panic handler

Rebased