golf cartpaths: add field to choose hw tag

and use highway=footway for walking paths

data/fields/highway_cartpath.json

@@ -0,0 +1,12 @@
+{
+    "key": "highway",
+    "type": "typeCombo",
+    "label": "Type of Path",
+    "strings": {
+        "options": {
+            "path": "Cartpath",
+            "service": "Service Road"
+        }
+    },
+    "autoSuggestions": false
+}