RFR: 8297213: Robot capture tests should move mouse to corner of screen

[Andy Goryachev]

Added Util.parkCursor(Robot) method to move the cursor to lower left corner (while avoiding dock, tray, or active corners).

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Commit messages:
 - 8297213: park cursor

Changes: https://git.openjdk.org/jfx/pull/955/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=955&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8297213
  Stats: 71 lines in 7 files changed: 49 ins; 16 del; 6 mod
  Patch: https://git.openjdk.org/jfx/pull/955.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/955/head:pull/955

PR: https://git.openjdk.org/jfx/pull/955