Split valkey.log and audit.log

[LiiNen]

fix #260

what have been changed

• Add config parameter "audit-logfile", usage is same as "logfile".
• If "audit-logfile" is not empty and server.verbosity bigger than LL_VERBOSE, edit it as LL_VERBOSE.
• If loglevel == LL_VERBOSE and server.verbosity == LL_VERBOSE, print it to "audit-logfile", not "logfile".

results

with valkey.conf as below:

# valkey.conf
logfile "./valkey.log"
audit-logfile "./audit.log"

Note

• also wrote in [NEW] Splitting logfile for auditing #260
• LL_DEBUG is not included in this change: not affected by this change.
  • It's intended because DEBUG is literally debug.
• I would like to add more log levels: like splitting client connection logs with other verbose logs.
  • But this is a quite big change, so I didn't do it right now.
• testfile is not ready cause it is just a concept of change. I'll work on it when this change is suitable for Valkey.