Implement auth feature

[Hajbo]

Clear and concise description of the problem

Implement auth related endpoints. Start with the blocking ones, the rest can be added at a later point separately.

Suggested solution

• Add user schema
• Add related endpoints:
  • Login
  • Registration
• Inject user to request context and implement an auth guard

Alternative

No response

Additional context

No response

Validations

• Read the Contributing Guide.
• Read the README.md.
• Check that there isn't already an issue that requests the same feature.