Add long running traces to flare report, allow flare files to be downloaded with JMX#9874

deejgregor wants to merge 6 commits intoDataDog:masterDataDog/dd-trace-java:masterfrom

deejgregor:pending-traces-jmx-dumpdeejgregor/dd-trace-java:pending-traces-jmx-dumpCopy head branch name to clipboard