Fix Gender Values with Extensions Not Found in CQL

[alexanderkiel]

In case one uses extensions on the primitive code value of gender like in this patient resource:

{
  "resourceType": "Patient",
  "id": "0",
  "gender": "female",
  "_gender": {
    "extension": [
      {
        "url": "http://fhir.de/StructureDefinition/gender-amtlich-de",
        "valueCoding": {
          "system": "http://fhir.de/CodeSystem/gender-amtlich-de",
          "code": "W",
          "display": "weiblich"
        }
      }
    ]
  }
}

CQL doesn't see the value female and so doesn't match the resource on queries like this:

define InInitialPopulation:
  Patient.gender = 'female'

[alexanderkiel]

Fixed in #992