RFR: 7904004: Run jtreg GHA workflows for FreeBSD [v2]

[snake66]

> GitHub Actions does not natively support FreeBSD, so we use the vmactions/freebsd-vm action as a base to run the tests in a VM under an Ubuntu runner.
> 
> This work is sponsored by The FreeBSD Foundation.

snake66 has updated the pull request incrementally with one additional commit since the last revision:

  Split long line in workflow

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

Changes:
  - all: https://git.openjdk.org/jtreg/pull/262/files
  - new: https://git.openjdk.org/jtreg/pull/262/files/0788637c..d8f66b75

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jtreg&pr=262&range=01
 - incr: https://webrevs.openjdk.org/?repo=jtreg&pr=262&range=00-01

  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jtreg/pull/262.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/262/head:pull/262

PR: https://git.openjdk.org/jtreg/pull/262