Background
The JRockit JDK has a framework for issuing diagnostics commands to the JVM. The framework has a command line tool called jrcmd, a JMX interface and a ctrl-break handler with configuration file and signal handler.

The goal of this CR is to provide a similar feature to HotSpot with:
     - a diagnostics command framework that supports a command line tool and JMX interface.
     - a support for public, closed/licensed and hidden diagnostic commands.
     - a command line tool called jcmd that allows execution of all diagnostic commands.
     - an equivalent to the JRockit JDK diagnostics command “version” and "help" must be implemented to demonstrate and test the features of the framework
     
Note:
Other diagnostics commands that can be executed with this framework are not in scope of this CR.