Function run 

pub async fn run(
    roles: RoleSet,
    config: Arc<Config>,
    database: Arc<Database>,
) -> Result<()>

Binds the configured sockets and runs the server until a shutdown signal arrives: the whole of acme-proxy serve.

Every failure is logged here — server_socket_bind_failed for the ACME socket, server_fatal_error for anything after it — and returned for the caller to turn into an exit status.