Expose JVM debugging via command-line argument

Recently I have been performing remote JVM debugging on a number of NiFi components – core instances, etc. Currently, to enable/disable JVM debugging requires manually modifying the bootstrap.conf file or the *.sh file and (un)commenting/adding the following line(s):

bootstrap.conf

java.arg.debug=-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000

I propose we decide on a standard command-line flag or environment variable which can be set to enable/disable JVM debugging (and optional flag/variable to enable/disable suspend) in order to make this easier for developers.

My suggestion is to follow a pattern like Kafka uses, as proposed in this StackOverflow answer.

This can be copied to NiFi Registry, MiNiFi Java, etc.