RFR: 8306133: Open source few AWT Drag & Drop related tests [v2]

[Damon Nguyen]

> This PR open sources few AWT DnD related tests

Damon Nguyen has updated the pull request incrementally with one additional commit since the last revision:

  Remove endline. Add frame titles. Dispose in EDT.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13591/files
  - new: https://git.openjdk.org/jdk/pull/13591/files/90e7447d..c9194563

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13591&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13591&range=00-01

  Stats: 47 lines in 5 files changed: 2 ins; 5 del; 40 mod
  Patch: https://git.openjdk.org/jdk/pull/13591.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13591/head:pull/13591

PR: https://git.openjdk.org/jdk/pull/13591