[jfx23] RFR: 8335630: Crash if Platform::exit called with fullScreen Stage on macOS 14

[Kevin Rushforth]

Clean backport of this crash-on-exit fix to the `jfx23` stabilization branch.

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Commit messages:
 - Backport 81f11c4a39eb505d17c57a49c5e084f75a169856

Changes: https://git.openjdk.org/jfx/pull/1511/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1511&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8335630
  Stats: 157 lines in 4 files changed: 130 ins; 0 del; 27 mod
  Patch: https://git.openjdk.org/jfx/pull/1511.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1511/head:pull/1511

PR: https://git.openjdk.org/jfx/pull/1511