RFR: 8358468: Enhance code consistency: java.desktop/macos

[Sergey Bylokhov]

This PR updates the last (!!) remaining platform-specific part of the java.desktop module: macos.
The unix/windows were previously addressed in: https://github.com/openjdk/jdk/pull/24170 , https://github.com/openjdk/jdk/pull/24941 and https://github.com/openjdk/jdk/pull/25439.

Note: Unlike on other platforms, the initial change for macOS caused the "BadSerializationTest" to fail. This test relies on internal details of the Aqua Look & Feel that were previously exposed via serialized data (and already [fails](https://bugs.openjdk.org/browse/JDK-8277817) on other platforms). Adding the final modifier to the class changes its serialVersionUID, which triggered the failure even on macOS.
To avoid this issue, I have reverted the changes to those internal classes for now, see https://github.com/openjdk/jdk/pull/25607/commits/ff7e64b6e38a1a809d434628f304e49408135697

To download the diff file and filter only the modified lines you can use the following script:


curl -s https://patch-diff.githubusercontent.com/raw/openjdk/jdk/pull/25607.diff -o d.txt && grep -E '^+|^-' d.txt | grep -vE '^+++|^---'

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The `java.desktop` module currently lacks proper use of the `@Override` annotation for methods and the `final` modifier for classes. While similar changes were previously made in the [JavaSound](https://github.com/openjdk/jdk/commit/e0c7d59246cf36644d494eced76e4b9d96ff1ded#diff-ae3e5f9c40fe25ef03e7a89844de174ef5c15e6179d769e2a4bcb7e73688c9b5), [java.desktop/windows](https://github.com/openjdk/jdk/pull/24170) (and some of the classes on demand), these changes are not as critical now due to the new jdk "encapsulation", but they are still useful for improving code consistency.

The public API was not affected so there is no need to worry about a CSR

Note: I will submit additional patches in this area later because:

1. Only lines with `@Override` and `final` were modified to keep the diff clear - header dates were not updated (that could be covered by one patch similar to [this](https://bugs.openjdk.org/browse/JDK-8345797))
2. I skipped adding `@Override` for anonymous classes

Any feedback or suggestions are welcome!

Here is a [link](https://patch-diff.githubusercontent.com/raw/openjdk/jdk/pull/25607.diff) to a simple diff file, it might be more convenient for reviewing the changes.

The build was successful, and I ran all the open jtreg tests without issues. But it's possible that some closed tests may be affected by these changes. It would be good to verify this by mach5 to ensure everything works as expected.

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Commit messages:
 - Fix java/awt/dnd/BadSerializationTest/BadSerializationTest.java test
 - restore formatting
 - final in java.desktop/macos
 - override in java.desktop/macos

Changes: https://git.openjdk.org/jdk/pull/25607/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25607&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8358468
  Stats: 1216 lines in 169 files changed: 859 ins; 0 del; 357 mod
  Patch: https://git.openjdk.org/jdk/pull/25607.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25607/head:pull/25607

PR: https://git.openjdk.org/jdk/pull/25607