feat: support flamegraphs in Java walltime#2

not-matthias wants to merge 12 commits intocod-2308-walltime-benchmarks-without-flamegraphsCodSpeedHQ/codspeed-jvm:cod-2308-walltime-benchmarks-without-flamegraphsfrom

cod-2309-walltime-benchmarks-with-flamegraphsCodSpeedHQ/codspeed-jvm:cod-2309-walltime-benchmarks-with-flamegraphsCopy head branch name to clipboard