refactoring the project

[FoHoOV]

The backend project could be much simpler. I should do something about it, but I don't know what. Will update the issue as I start working on it.

Main areas I want to work on:

1. schemas and their namings
2. the way api params are passed to db level (their namings and the number of params)
3. repetitive code for validations and inputs/outputs
4. test suite

SIDE NOTE:
this is actually not part of this, but it would be awsome if each frontend depended on the backend deployed on that specific PR (see this)

[FoHoOV]

Good enough, I'll do the rest as I go on