RFR: 8316813: NMT: Using WhiteBox API, virtual memory tracking should also be stressed in JMH tests [v2]

[Afshin Zafari]

> After WhiteBox (`wb.jar`) is added to the lib-test, it is possible to use it in Java benchmarks. This PR uses WhiteBox to access and call directly NMT API and measure their performance in stressed circumstances.

Afshin Zafari has updated the pull request incrementally with one additional commit since the last revision:

  better names for variables used.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/17582/files
  - new: https://git.openjdk.org/jdk/pull/17582/files/4de3c09e..9467a95c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17582&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17582&range=00-01

  Stats: 6 lines in 1 file changed: 0 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/17582.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17582/head:pull/17582

PR: https://git.openjdk.org/jdk/pull/17582