[jdk21u-dev] RFR: 8328484: Convert and Opensource few JFileChooser applet test to main

[Goetz Lindenmaier]

I backport this for parity with 21.0.8-oracle

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Commit messages:
 - Backport 528efe206d5ee3775b01f3b90600ca3cab6c96f0

Changes: https://git.openjdk.org/jdk21u-dev/pull/1559/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1559&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328484
  Stats: 442 lines in 3 files changed: 442 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1559.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1559/head:pull/1559

PR: https://git.openjdk.org/jdk21u-dev/pull/1559