Ensure correct gender code is set

[ibacher]

When creating a new patient, a request is sent out to the MPI to search for matching patients. This search encodes the gender (where populated) incorrectly. For instance, searching:

localhost:5001/fhir/Patient?family%3Acontains=Lalka&given%3Acontains=Ale&gender=F&address-state%3Acontains=-&address-city%3Acontains=-&_include=Patient%3Alink&_format=json

Note that gender is queried for if it is F. The FHIR valueset for administrative gender specifies that this should be female.