[jdk21u-dev] RFR: 8340985: Open source some Desktop related tests

[Goetz Lindenmaier]

I backport this for parity with 21.0.8-oracle

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Commit messages:
 - Backport 172f74466fe59ece816764112dba98e4604706b7

Changes: https://git.openjdk.org/jdk21u-dev/pull/1511/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1511&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8340985
  Stats: 580 lines in 5 files changed: 580 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1511.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1511/head:pull/1511

PR: https://git.openjdk.org/jdk21u-dev/pull/1511