[jdk25u-dev] RFR: 8286258: [Accessibility, macOS, VoiceOver] VoiceOver reads the spinner value wrong and sometime partially

[Roland Mesde]

Backporting JDK-8286258: [Accessibility,macOS,VoiceOver] VoiceOver reads the spinner value wrong and sometime partially.

This PR fixes VoiceOver on macOS incorrectly announcing JSpinner values by suppressing spurious edit-related events from the embedded text field and generating correct accessibility notifications when the spinner value changes programmatically.

For parity with Oracle JDK.

Ran related tests on linux-x64, linux-aarch64, macos-aarch64 and windows-x64:

```../jtreg/build/images/jtreg/bin/jtreg -jdk build/macosx-aarch64-server-release/images/jdk -m test/jdk/javax/accessibility/JSpinner/CustomSpinnerAccessibilityTest.java```

Screenshot:

<img width="851" height="709" alt="Screenshot 2026-02-25 at 10 56 04 AM" src="https://github.com/user-attachments/assets/aae50b11-9992-4a3e-ac6e-3aab0a351fc7" />

Result:

Success 

[CustomSpinnerAccessibilityTest.jtr.txt](https://github.com/user-attachments/files/25555156/CustomSpinnerAccessibilityTest.jtr.txt)

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Commit messages:
 - Backport 8c82b58db960a178566514731e1f8dcbc59b0161

Changes: https://git.openjdk.org/jdk25u-dev/pull/314/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk25u-dev&pr=314&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8286258
  Stats: 139 lines in 4 files changed: 135 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk25u-dev/pull/314.diff
  Fetch: git fetch https://git.openjdk.org/jdk25u-dev.git pull/314/head:pull/314

PR: https://git.openjdk.org/jdk25u-dev/pull/314