[jdk21u-dev] RFR: 8354418: Open source Swing tests Batch 4

[Satyen Subramaniam]

Backporting JDK-8354418: Open source Swing tests Batch 4. Adds three windows tests - two for the WindowDesktopManager and one for menu delimiters. Ran GHA Sanity Checks, local Tier 1 and 2, and new tests directly. Patch is clean. Backporting for parity with Oracle.

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Commit messages:
 - Backport dda4b5a4ade2e5d7225117e58fce4038bb0e0f1b

Changes: https://git.openjdk.org/jdk21u-dev/pull/2157/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2157&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8354418
  Stats: 291 lines in 3 files changed: 291 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2157.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2157/head:pull/2157

PR: https://git.openjdk.org/jdk21u-dev/pull/2157