RFR: 8330846: Add stacks of mounted virtual threads to the HotSpot thread dump [v8]

[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:

 - Cleanup test
   
   - Stop virtualthread
   - Remove unneeded imports
   - Remove modules that are not needed
 - Fix copyright year

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Changes:
  - all: https://git.openjdk.org/jdk/pull/19482/files
  - new: https://git.openjdk.org/jdk/pull/19482/files/9acbf29d..b122cc05

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19482&range=07
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19482&range=06-07

  Stats: 18 lines in 1 file changed: 1 ins; 9 del; 8 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