RFR: 8330846: Add stacks of mounted virtual threads to the HotSpot thread dump [v5]

[Inigo Mediavilla Saiz]

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

Inigo Mediavilla Saiz has updated the pull request incrementally with two additional commits since the last revision:

 - Update test/hotspot/jtreg/serviceability/dcmd/thread/PrintVirtualThreadTest.java
   
   Co-authored-by: Andrey Turbanov <turbanoff at gmail.com>
 - Use JavaThread::print_vthread_stack_on

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Changes:
  - all: https://git.openjdk.org/jdk/pull/19482/files
  - new: https://git.openjdk.org/jdk/pull/19482/files/76e6e58c..12a41a54

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19482&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19482&range=03-04

  Stats: 19 lines in 2 files changed: 0 ins; 17 del; 2 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