Solidify Exception format

[StruckCroissant]

Summary

In the interest of fully applying RFC9457 as the standard for error formats on this project, there's a couple updates that need to take place. Currently we're rolling our own problem data but we can most likely use the problem-spring-web library.

Acceptance criteria

• application/problem+json shall be the de-facto response type for exceptions
• All MSW mocks used for frontend development shall be updated
  • An environment which variable enables the MSW in the development environment may be added
• All necessary types/schemas must be updated
• The problem-spring-web library shall be imported and set up