Implement gateway proper error handling when can't listen on port

[teon]

Description

If gateway can't bind an a port it doesn't return a proper error bug crashes:

defguard-gateway-1  | 
defguard-gateway-1  | thread 'main' (1) panicked at /usr/local/cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tokio-1.50.0/src/signal/unix.rs:71:53:
defguard-gateway-1  | failed to create UnixStream: Os { code: 13, kind: PermissionDenied, message: "Permission denied" }
defguard-gateway-1  | note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Implement a proper error handling and error message:

Can't bind to port XXX - please check if there maybe other services are running at this port, or if gateway has proper system privileges (seccomp or apparmor).