Option to omit event type prefix in logs

[RodolfoAndre]

Is your feature request related to a problem? Please describe.
I am in a process to improve security of an application using ESAPI library. I've noticed that there is an obligatory prefix that, since I have a huge infrastructure, the event type prefix would increase our cost because we use a paid monitoring service.

Describe the solution you'd like
It would help us if there was an optional property in ESAPI.properties file to indicate if the event type prefix log should be included or not when printing logs. (Just from the log message)

Describe alternatives you've considered including other security libraries
An alternative would be when all properties related to prefix append (logUserInfo, logClientInfo, logServerIp, logApplicationName) and the appName is empty or null, this prefix would not be included.

Additional context
I've had a discussion with kwwall with some ideas. I will fork the repo and send the pull request as an example.

[kwwall]

Reference to Discussion #810.