jvm metrics improvment

[FrankChen021]

1. report processCpuTime along with existing processCpuLoad so that it's easier and simpler for aggregations
   in next step, the processCpuLoad will be deprecated from the agent side and it will be defined as an expression to be calculated from processCpuTime and processors
2. report startedThreads, which is the number of threads starting in a given interval. this is an aggretable metric that makes query simpler.
   use getTotalStartedThreadCount to get diff between intervals
3. report finishedThreads, which is the number of threads shutdown in a given interval. this is an aggretable metric that makes query simpler

    finishedThreads = activeThreadsLast + startedThreads - activeThreadsNow
   

4. report deadLockThread which is a gauge metric indicating the number of dead locked threads