RFR: 8286822: Write a test to check the DND functionality between two InternalFrames

[Manukumar V S]

This test verifies that dragging from one InternalFrame and a drop target in another InternalFrame functions properly.
This fix moves an unstable closed applet based test to open regression based java test, but updated to be more comprehensive with some stabilisation improvements. The closed test was creating noise in CI as it often fails in Windows platform, especially in Windows 11.

Testing:
1. Tested using mach5 20 times per platform and got all Pass.
2. Tested using mach5 5 times specifically on Windows 11 and got all Pass.

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Commit messages:
 - 8286822: Write a test to check the DND functionality between two InternalFrames

Changes: https://git.openjdk.java.net/jdk/pull/8753/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8753&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8286822
  Stats: 384 lines in 1 file changed: 384 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8753.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8753/head:pull/8753

PR: https://git.openjdk.java.net/jdk/pull/8753