[jdk21u-dev] RFR: 8316306: Open source and convert manual Swing test

[Andrew Lu]

I backport this for parity with 21.0.5-oracle.

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Commit messages:
 - Backport d3e821838668a0ccc0ccd098336230975e27fd7c

Changes: https://git.openjdk.org/jdk21u-dev/pull/778/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=778&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8316306
  Stats: 82 lines in 1 file changed: 82 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/778.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/778/head:pull/778

PR: https://git.openjdk.org/jdk21u-dev/pull/778