RFR: JDK-8328225: Convert ImageDecoratedDnD.html applet test to main

[Harshitha Onkar]

Following test is converted to main using PassFailJFrame.

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Commit messages:
 - EOF newline added
 - Instructions updated
 - applet to main

Changes: https://git.openjdk.org/jdk/pull/18315/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18315&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328225
  Stats: 247 lines in 2 files changed: 45 ins; 186 del; 16 mod
  Patch: https://git.openjdk.org/jdk/pull/18315.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18315/head:pull/18315

PR: https://git.openjdk.org/jdk/pull/18315