Migration to Spring Boot 3

[dabico]

Closes #159

Checklist:

• [ ] Upgrade Java version to 21
• [X] Update Spring Boot dependencies
• [X] Update Spring Boot Admin dependencies
• [X] Update Spring Doc OpenAPI dependencies
• [X] Update Hibernate dependencies
  • [X] Relocate core and modelgen
  • [X] Relocate validation utils
• [X] Relocate javax to jakarta
• [X] Relocate @ConstructorBinding
• [X] Replace deprecations for:
  • [X] Spring Data
  • [X] Spring Retry
  • [X] Spring Security
  • [X] Spring Scheduling
  • [X] Spring Actuator
• [ ] Update /download endpoint to use StreamingResponseBody
• [ ] Add support for native image compilation with GraalVM
• [ ] Add support for virtual threads courtesy of project Loom