Improve radicle-node panics — heartwood

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.

¹

https://github.com/pragma-org/amaru/blob/41ba1c26f82c813dfd052f9bc2adeb55dcd5957c/crates/amaru/src/bin/amaru/panic.rs#L17

 }
 fn main() {
     // If `RUST_BACKTRACE` does not have a value, then we set it to capture
     // backtraces for better debugging, otherwise we keep the environments
     // value.
     const RUST_BACKTRACE: &str = "RUST_BACKTRACE";
     if std::env::var_os(RUST_BACKTRACE).is_none() {
         std::env::set_var(RUST_BACKTRACE, "1");
     }
     if let Err(err) = execute() {
         if log::log_enabled!(target: "node", log::Level::Error) {
             log::error!(target: "node", "Fatal: {err:#}");
         } else {
             eprintln!("Error: {err:#}");
         }
         log::error!(target: "node", "{err:#}");
         process::exit(1);
     }
 }