RFR: 8330846: Add stacks of mounted virtual threads to the HotSpot thread dump [v9]

[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:

 - Remove dead code
 - Remove extra indentation (leave it for the next PR)

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/19482/files
  - new: https://git.openjdk.org/jdk/pull/19482/files/b122cc05..7a57d05d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19482&range=08
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19482&range=07-08

  Stats: 8 lines in 2 files changed: 0 ins; 7 del; 1 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