Refactor Notification system to extract the code for connecting to the message broker into a new class library

[Maxvanhattum]

Describe the bug
At the moment the Notificationsystem is a console application, which listens to the message broker and sends an email based on payloads. In this console application there is also code present for connecting/subscribing/listening to the message broker.
This code can AND is already reused in different places (jobscheduler and recommendationsystem), these applications now import all the code from the Notificationsystem console application, however they only use the parts to connect to the message broker.

Expected behavior
Applications that want to utilize the message broker service should only need to import the bare minimum code necessary for this to happen. Therefor this code should be separated into its own class library. The notification system (email based) should get a new dependency on this class library.
Other application should change their dependency to the new class library.

[niraymak]

Waiting for recommendation system