ggml-rpc-server logging

[AE86takumi-ai]

I'm trying to debug ggml-rpc-server across multiple co-worker PCs, so it's hard to see all the terminals. I couldnt find any verbosity/log-level option and it all outputs to stderr. I'd like to pipe true error logs to a shared folder. so request is to either add verbosity/log-level option, or separate outputs to stderr and stdout.