Handling multiple matched addresses in Census geocoding API

[ngriffiths21]

The Census geocoder API can return multiple matched addresses. Our handler already checks all returned values for eligibility, but in a potentially confusing way because it checks if any match is eligible.

For example Boston has lots of Washington Streets, so the address "120 washington st boston ma" matches in five places (!) scattered around Boston, and the corresponding matchedAddress fields really are matches in different zip codes. I googled a few matches and found that some don't look active, i.e. Google locates them in between two buildings and the numbering skips over them. The user doesn't get an indication of which match led to eligibility.

The autocompleted addresses are probably fine because they have zip codes, so that partly sidesteps the problem, but maybe we should make multiple matches an error, or indicate which match was used, or make autocomplete the only search mechanism.