RFR: JDK-8328379 : Convert URLDragTest.html applet test to main

[Harshitha Onkar]

Following test - test/jdk/java/awt/dnd/URLDragTest/URLDragTest.html is converted from applet to main using PassFailJFrame. 

PassFailJFrame's `logArea()` is used for logging messages.

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Commit messages:
 - test changes: applet to main
 - html file deleted
 - test moved

Changes: https://git.openjdk.org/jdk/pull/18364/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18364&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328379
  Stats: 227 lines in 3 files changed: 94 ins; 133 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/18364.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18364/head:pull/18364

PR: https://git.openjdk.org/jdk/pull/18364