Add hidden preset for shop=ice_cream referencing amenity=ice_cream

these are effectively the same thing (though there were attempts to argue for obscure differences - disclaimer: I participated in these discussions)
this adds no work for translators
shop=ice_cream should be supported somehow either way

BTW, I prefer shop=ice_cream over amenity=ice_cream but I guess that I should focus on more useful things than tagfiddling this one

fixes part of #1641 - alternative would be to add this tag to list of ignored and unsupported ones

Author: matkoniecz

data/presets/shop/_ice_cream.json

@@ -0,0 +1,19 @@
+{
+    "icon": "fas-ice-cream",
+    "geometry": [
+        "point",
+        "area"
+    ],
+    "fields": [
+        "{amenity/ice_cream}"
+    ],
+    "moreFields": [
+        "{amenity/ice_cream}"
+    ],
+    "tags": {
+        "shop": "ice_cream"
+    },
+    "matchScore": 0.5,
+    "name": "{amenity/ice_cream}",
+    "searchable": false
+}