Split the endpoint test to multiple files

[bfabio]

main_test.go is getting bigger and confusing to navigate.

A single test file for each resource would be nice to have, if that's something we can do without complicating the structure.

[ludovicobesana]

@bfabio Hello, if you need some help here i can help you with the one

[bfabio]

@ludovicobesana hey 👋, it'd be great if you want to take on this bug!

The problem here is that main_test.go is really big (and it'll hopefully grow in the future).

It has tests for all the resources (fe. TestPublishersEndpoints for publishers enpoints, TestLogsEndpoints for logs endpoints and so on) but having all of them in a single file gets us to a 3k lines file which is also getting difficult to navigate.

In addition, all the resources should have more or less the same tests (fe. GET, POST, PATCH, DELETE and combinations for required fields, common errors, etc.) and having those in separate files would make it easy to see if a resource is missing tests that we do on another resource.