Create unit tests for `/packages/api`

[NicoSerranoP]

Motivation

We are moving all the p0tion coordinator infrastructure to a single server application (API). This new API was built using NestJS and we are missing unit tests.

Details

Write unit tests for each route (endpoint) in the different modules (auth, ceremonies, circuits, participants, storage and users). Remember to check the following:

1. There is some data (circuits, zkeys, etc) that could be used from @actions or duplicate it into /api
2. The functions should finalize correctly in normal scenarios
3. Some unit tests might require concurrent requests to check everything works as expected

Tutorial to setup the API Coordinator application

[NathaliaBarreiros]

Hey @NicoSerranoP!

I'm interested in this issue and would like to request assignment. Let you know if I have any question.