[jdk11u-dev] RFR: 8306466: Open source more AWT Drag & Drop related tests

[Antonio Vieiro]

Clean backport of [JDK-8306466](https://bugs.openjdk.org/browse/JDK-8306466) for parity with Oracle 11.0.24.

All five tests pass in Linux/Gnome and Windows 11.

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Commit messages:
 - Backport 418a82551a2c58e43963beb5aa242a58bbd30e2f

Changes: https://git.openjdk.org/jdk11u-dev/pull/2810/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2810&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306466
  Stats: 848 lines in 8 files changed: 848 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2810.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2810/head:pull/2810

PR: https://git.openjdk.org/jdk11u-dev/pull/2810