RFR: CODETOOLS-7903464: add VirtualThreadExecutor to the list of predefined worker threads executors

[Sergey Kuksenko]

The list of working threads executors should be expanded with virtual threads executor.
Added VIRTUAL_TPE which is  "Executors.newFixedThreadPool(maxThreads, virtualThreadFactory)).

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Commit messages:
 - CODETOOLS-7903464: added virtual threads executor

Changes: https://git.openjdk.org/jmh/pull/102/files
 Webrev: https://webrevs.openjdk.org/?repo=jmh&pr=102&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903464
  Stats: 139 lines in 3 files changed: 87 ins; 50 del; 2 mod
  Patch: https://git.openjdk.org/jmh/pull/102.diff
  Fetch: git fetch https://git.openjdk.org/jmh.git pull/102/head:pull/102

PR: https://git.openjdk.org/jmh/pull/102