RFR: 8328570: Convert closed JViewport manual applet tests to main

[Prasanta Sadhukhan]

Few closed manual applet JViewport tests are converted to main based and opensourced

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Commit messages:
 - 8328570: Convert closed JViewport manual applet tests to main

Changes: https://git.openjdk.org/jdk/pull/18418/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18418&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328570
  Stats: 429 lines in 5 files changed: 429 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/18418.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18418/head:pull/18418

PR: https://git.openjdk.org/jdk/pull/18418