use "manyCombo" field for "gender" field, restrict hairdressers to female/male, closes #894

also partially addresses #895 and https://github.com/openstreetmap/iD/issues/7427: for that iD should actually also show the "no" values allow explicitly marking the absense of certain options

data/fields/gender.json

@@ -1,5 +1,5 @@
 {
-    "type": "radio",
+    "type": "manyCombo",
     "keys": [
         "male",
         "female",

data/fields/gender_simple.json

@@ -0,0 +1,13 @@
+{
+    "type": "manyCombo",
+    "keys": [
+        "female",
+        "male"
+    ],
+    "label": "{gender}",
+    "stringsCrossReference": "{gender}",
+    "options": [
+        "female",
+        "male"
+    ]
+}