Add an interface for AvaTaxClient

[mweylandcliq]

Please expose an interface for the AvaTaxClient. In order to build out proper unit test and allow a AvaTaxClient instance to be injectable this should really implement an interface.

[MattMinke]

It would also be nice to have some interface segregation. https://en.wikipedia.org/wiki/Interface_segregation_principle

[svc-developer]

Thanks for the suggestion. We will review this idea.

[nls-aarndt]

Hi, any update on this? Seems like there is a PR that was submitted about two years ago that is still open (but with conflicts now)

#153

We need an interface on the AvaTaxClient in order to mock it in unit tests.

[svc-developer]

I think this got closed by accident, will review it.

[svc-developer]

Released with 24.4.1, please check it out