Integrate Spring Modulith in `application-server`

[GODrums]

Motivation

Spring Modulith allows for module-driven development in a Spring project including internal and API-exposed parts within a module. It provides event management for cross-module communication and integration testing functionality.

Description

Adds the core packages of Spring Modulith to the Application Server. Added tests include a module integrity verification (according to https://docs.spring.io/spring-modulith/reference/verification.html) as well as UML diagram generation.

Resources for used modules/JARs

• https://docs.spring.io/spring-modulith/reference/appendix.html#artifacts

Checklist

General

• [x] PR title is clear and descriptive
• [x] PR description explains the purpose and changes
• [x] Code follows project coding standards
• [x] Self-review of the code has been done
• [x] Changes have been tested locally
• [ ] Screenshots have been attached (if applicable)
• [ ] Documentation has been updated (if applicable)

Server (if applicable)

• [x] Code is performant and follows best practices
• [x] No security vulnerabilities introduced
• [ ] Proper error handling has been implemented
• [x] Added tests for new functionality
• [ ] Changes have been tested in different environments (if applicable)