RFR: 8307297: Move some DnD tests to open

[Alisen Chung]

Adding some DnD tests

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Commit messages:
 - removed extra layer of directories
 - added tests

Changes: https://git.openjdk.org/jdk/pull/13756/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13756&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8307297
  Stats: 1241 lines in 7 files changed: 1241 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/13756.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13756/head:pull/13756

PR: https://git.openjdk.org/jdk/pull/13756