RFR: 8365708: Add missing @Override annotations to WindowsMenuItemUIAccessor

[Alexey Ivanov]

Add the missing `@Override` annotations to anonymous classes implementing `WindowsMenuItemUIAccessor`.

PR #24170 for [JDK-8352638](https://bugs.openjdk.org/browse/JDK-8352638) added the `@Override` annotations to `getMenuItem` and `getPart` but left `getState` without the annotation.

For consistency, add the annotation to the `getState` method too.

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Commit messages:
 - 8365708: Add missing @Override annotations to WindowsMenuItemUIAccessor

Changes: https://git.openjdk.org/jdk/pull/26828/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26828&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8365708
  Stats: 5 lines in 4 files changed: 4 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/26828.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26828/head:pull/26828

PR: https://git.openjdk.org/jdk/pull/26828