feat: ✨ http exceptions and default exception handlers

[lucas-labs]

Implement changes as proposed on #4

• Implement exception handling, with schema responses similar to nestjs + http exceptions
• Patch openai schemas to accordingly reflect the changes (http 400 for request validation errors and the new common schema for errors replicating those of nestjs)

Note

Just that for now, as we depend on #6 to be able to implement per-controller exception handlers (and to even think on a
per-route functionality)
Nest equivalent functionality