Update dependencies, improve JSON conversion handling, and refactor API endpoints

- Adjust dependencies in `pom.xml`: downgrade Spring Boot version, reorganize and optimize dependencies.
- Replace outdated import paths with revised Jackson and Spring classes.
- Improve error handling in `JsonMapConverter` using `try-catch` for JSON processing.
- Refactor `StepEditorController` endpoints for better clarity and standardization.
- Minor updates in tests for compatibility.