RFR: CODETOOLS-7902927: JMH: Support HTML flamegraphs for async-profiler [v2]

[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.

Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:

  Simplify

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Changes:
  - all: https://git.openjdk.java.net/jmh/pull/36/files
  - new: https://git.openjdk.java.net/jmh/pull/36/files/1f0aadc2..a77ff455

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jmh&pr=36&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jmh&pr=36&range=00-01

  Stats: 44 lines in 2 files changed: 2 ins; 40 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