[Core] Tee the output of `ray start --block` to log file as well

[jjyao]

Description

One nice thing about ray start --block is that it will print out the exit code of processes that it starts such as raylet so if raylet is kill -9ed then we will know from the output. This is very useful to figure out why raylet crashes in some cases. Currently it's only send to stdout but if users don't save it, it's lost. We should also tee the logs to a log file as well.

Use case

No response

[nadongjun]

May I give this a try?