Added unique title validation for News entities

[darkravchuk]

Summary of Issue

The main issue involves adding validation to ensure that News entities have unique titles within the system. The current implementation lacks a check, which allows duplicate news entries with the same title, leading to potential conflicts and confusion when managing content.

Summary of Change

• Implemented a validation check that prevents duplicate titles when creating or updating a News entity.
• Modified the form to validate title uniqueness before submission.
• Adjusted the error handling logic to notify the user if a duplicate title is detected.

[sonarqubecloud]

Quality Gate failed

Failed conditions
28.6% Coverage on New Code (required ≥ 80%)
52.7% Duplication on New Code (required ≤ 3%)

See analysis details on SonarCloud