Add mongo integration tests

[michelaquino]

Description

Add integration test suit for MongoDB

Closes 579

Proposed Changes

This PR introduces an integration test suite for MongoDB. The focus are the files mongo.go, huskydb.go and huskystats.go. These files contains the main functions related to MongoDB connection and queries. An integration test workflow was added on Github Actions.

Two unit tests that were failing were modified as well:

1. One unit test in the file api/util/api/api_test.go was fixed. The problem was a missing configuration.

2. Another one in the file api/token/token_test.go was removed, the one with the description "When GetValidHashFunction returns a false boolean". The function GetValidHashFunction isn't called by the function GenerateAccessToken, the one that the unit test is related to.

Testing

To run the integration tests, the Docker need to be running:

$ make test
$ make integration-test-compose-up
$ make integration-test
$ make integration-test-compose-down

[fguisso]

Let's use more real data, running in your local, starting some analysis, then use data similar to what you got. If you don't get some cases, I can provide you with other examples.

[michelaquino]

Sure, I'll change the data. If it's not a problem, it would be nice to provide these examples.