Class library MessageBrokerPublisher retrieves connection parameters itself

[Maxvanhattum]

Describe the bug
Class library MessageBrokerPublisher retrieves connection parameters itself, while it should be passed in by the services that imports this library.

To Reproduce
Steps to reproduce the behavior:

1. Go to MessageBrokerPublisher project
2. Open folder Services
3. Open RabbitMQConnectionFactory.cs
4. Look at lines 27/28/29 and lines 38/39/40

Expected behavior
The RabbitMQConnectionFactory should accepts these values in the constructor, instead of trying to retrieve them from the environment. And it should not check if these values are set in the environment, delegating this to the service utilizing this library (preferably the service uses an appsettings.json file, overriding the values if environment variables are set.