Add fair lock policy to @Locked via @Locked.Policy

[vulinh64]

Hi Lombok team,

This is my first contribution, and thank you for taking the time to review it.

This PR adds class-level lock fairness configuration through:

@Locked.Policy(fairness = true)

When present, Lombok generates fair locks for the class:

• @Locked -> new ReentrantLock(true)
• @Locked.Read / @Locked.Write -> a shared new ReentrantReadWriteLock(true)

By default, ReentrantLock and ReentrantReadWriteLock are non-fair, and Lombok’s existing behavior remains unchanged. The policy only affects locks generated by Lombok; explicitly named locks and user-declared lock fields are deliberately left untouched.

With JDK 25 that fixed the pinned synchronized issue, the usage of @Locked can still be attractive with the optional fairness policy.

The implementation includes javac and Eclipse support, transform tests for generated and named locks, and documentation/usage-example updates.

I would appreciate feedback on the API and implementation choices.