Provide support for Managed Identity authentication

[meersschautarnaud]

Is your feature request related to a problem? Please describe.
Since the ServiceBus message pump can be registered using Managed Identity authentication I would like to have support for this when registering a CloudEventBackgroundJob.

Describe the solution you'd like
A new extension method that enables to make use of Managed Identity authentication.

[stijnmoreels]

Aha aha, yes, that's a good one we forgot. Thank you for the issue! Would you like to contribute this?

[meersschautarnaud]

Yes, I would like that! 😄

[stijnmoreels]

Ok, great! We have a contribution guide if you feel lost, otherwise ping me in case of any problem. Thank you! ❤️