Small fixes

[bennypk1]

• fixed bug Ali pointed out in send message presenter
• Removed unnecessary User DAI for AddThread use case
• many checkstyle fixes, especially in data access

[Roppax]

This PR brings important changes, particularly in exception handling and API interactions. The enhancements in PingBackend and DAOs, like descriptive exception messages and refined JSON parsing, make the backend interactions more reliable. The addition of getThreadsByUsername in ThreadDataAccessObject is a good improvement, aligning well with use case requirements.

The changes in ChatView and ThreadsView show property change handling, which simplifies how updates are managed. Removing unnecessary code, such as unnecessary imports and unused interfaces, improves readability and maintainability across the project.

Overall, these updates improve the codebase's clarity. I believe that adding tests for the new DAO methods would be a helpful next step to make sure the changes hold up. Nice work!