Generalize restart functionality in message pumps with interface so it can be generally restarted

[stijnmoreels]

Is your feature request related to a problem? Please describe.
The background jobs functionality allows for message pumps to be restarted based on rotated credentials. With the addition of the Azure EventHubs message pump, such restart functionality could be useful there, too.

Describe the solution you'd like
Instead of hard-coding it on the Azure Service Bus message pump, we should expose something like a 'restart interface' that we can re-use across background jobs that want to restart a message pump. The background job registration then only needs the job ID and to identify which message pump it needs to restart, instead of now be hard-coded on the type of message pump it can restart.