Support repl-driven profiling flamegraph generation

[jeaye]

• Be able to run perf (or similar) from code (likely backed by a C++ fn)
• Port the stackcollapse-perf.pl to jank so we can collapse stacks
• Use clj-async-profiler's generate-flamegraph for the rest
  • We likely can't pull this whole thing in as a library without patching it to be cljc and using reader conditionals; start by copying the code, if that's easier
• Might need to implement spit for writing out the file

Current approach

echo -1 | sudo tee /proc/sys/kernel/perf_event_paranoid
perf record -g -F max ./build/jank run test.jank
perf script | ../third-party/FlameGraph/stackcollapse-perf.pl >| perf.data.folded
../third-party/FlameGraph/flamegraph.pl --width 1920 --colors java perf.data.folded >| perf.svg