RFR: 8340966: Open source few Checkbox and Cursor tests - Set1

[Damon Nguyen]

Following tests are added as part of this PR:

./java/awt/CheckboxGroup/DynamicChangeTest/DynamicChangeTest.java - MANUAL
./java/awt/Cursor/NullCursorTest/NullCursorTest.java - MANUAL
./java/awt/Cursor/HiddenDialogParentTest/HiddenDialogParentTest.java - MANUAL
./java/awt/Cursor/CursorDragTest/ListDragCursor.java - MANUAL
./java/awt/Cursor/InvalidImageCustomCursorTest/InvalidImageCustomCursorTest.java - MANUAL

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Commit messages:
 - Remove original bug description from instructions
 - Initial commit

Changes: https://git.openjdk.org/jdk/pull/21336/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21336&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8340966
  Stats: 477 lines in 5 files changed: 477 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/21336.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21336/head:pull/21336

PR: https://git.openjdk.org/jdk/pull/21336