RFR: 8306681: Open source more AWT DnD related tests

[Damon Nguyen]

This PR open sources more AWT DnD related tests

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Commit messages:
 - Initial test move

Changes: https://git.openjdk.org/jdk/pull/13674/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13674&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306681
  Stats: 545 lines in 7 files changed: 545 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/13674.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13674/head:pull/13674

PR: https://git.openjdk.org/jdk/pull/13674