Processing of incomplete addresses

[giacecco]

Although many components of the platform and its data models are already designed to manage incomplete addresses, most of its public interfaces did not allow for incomplete addresses to be processed, e.g. you could not process postcode-less addresses using Sorting Office.

We will use this sprint for an end-to-end review of what components need adjustments to start processing incomplete addresses, and then actually start doing it.

FYI @peterkwells . I thought it was useful to make this step in the roadmap clear.