RFR: 8348936: [Accessibility,macOS,VoiceOver] VoiceOver doesn't announce untick on toggling the checkbox with "space" key on macOS

[Abhishek Kumar]

VoiceOver doesn't announce the _untick state_ when Checkbox is `deselected` using **space** key. When CheckBox is deselected, the state change is not notified to a11y client (VoiceOver) and so the state is not announced by VO. 

Screen Magnifier is also unable to magnify the unchecked state of JCheckBox due to same reason and is captured as separate bug [JDK-8345728](https://bugs.openjdk.org/browse/JDK-8345728).

Proposed fix is to send the state change notification to a11y client when checkbox is deselected, this resolves the problem for VoiceOver and Screen Magnifier.

Similar issue observed for JToggleButton. So, I extended the fix for JToggleButton as well.

The proposed change can be verified the manual test in the PR.

CI pipeline testing is `OK`, link posted in JBS.

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Commit messages:
 - Whitespace jcheck fix
 - Manual test and copyright year update
 - CheckBox and ToggleButton untick state fix

Changes: https://git.openjdk.org/jdk/pull/23436/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23436&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8348936
  Stats: 118 lines in 2 files changed: 115 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/23436.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23436/head:pull/23436

PR: https://git.openjdk.org/jdk/pull/23436