RFR: 8330846: Add stacks of mounted virtual threads to the HotSpot thread dump

[Inigo Mediavilla Saiz]

Print the stack traces of mounted virtual threads when calling `jcmd <pid> Thread.print`.

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Commit messages:
 - 8330846: Add stacks of mounted virtual threads to the HotSpot thread dump

Changes: https://git.openjdk.org/jdk/pull/19482/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19482&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8330846
  Stats: 117 lines in 2 files changed: 117 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/19482.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19482/head:pull/19482

PR: https://git.openjdk.org/jdk/pull/19482