RFR: CODETOOLS-7902927: JMH: Support HTML flamegraphs for async-profiler

[Aleksey Shipilev]

Turns out, newer async-profiler silently eats "-o svg", expecting "-o flamegraph". It now generates HTML flamegraphs too. We need to handle both new and old flamegraph styles.

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Commit messages:
 - Autodetect version and use appropriate "flamegraph" option
 - Fix async-profiler: use "flamegraph", not "svg"

Changes: https://git.openjdk.java.net/jmh/pull/36/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmh&pr=36&range=00
  Issue: https://bugs.openjdk.java.net/browse/CODETOOLS-7902927
  Stats: 100 lines in 2 files changed: 98 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jmh/pull/36.diff
  Fetch: git fetch https://git.openjdk.java.net/jmh pull/36/head:pull/36

PR: https://git.openjdk.java.net/jmh/pull/36