Changed classification of ice_cream and chocolate (#1628)

According to [OpenMapTiles Schema](https://openmaptiles.org/schema/) ice_cream should be a class, not a subclass of the shop, so I think it makes more sense to remove ice_cream from the shop class. I tested this, and after the change, both amenity=ice_cream and shop=ice_cream OSM tags get class=ice_cream + subclass=ice_cream, which is fine, because both OSM tags shop=ice_cream and amenity=ice_cream represents the same thing

The next thing I did was to change the color of the ice_cream icon.

layers/poi/poi.yaml

@@ -17,10 +17,10 @@ layer:
         and `kindergarten`. Or use the class `shop` to style all shops.
       values:
         shop:
-          subclass: ['accessories', 'antiques', 'beauty', 'bed', 'boutique', 'camera', 'carpet', 'charity', 'chemist',
+          subclass: ['accessories', 'antiques', 'beauty', 'bed', 'boutique', 'camera', 'carpet', 'charity', 'chemist', 'chocolate', 
                      'coffee', 'computer', 'convenience', 'confectionery', 'copyshop', 'cosmetics', 'garden_centre', 'doityourself',
                      'erotic', 'electronics', 'fabric', 'florist', 'frozen_food', 'furniture', 'video_games', 'video',
-                     'general', 'gift', 'hardware', 'hearing_aids', 'hifi', 'ice_cream', 'interior_decoration',
+                     'general', 'gift', 'hardware', 'hearing_aids', 'hifi', 'interior_decoration',
                      'jewelry', 'kiosk', 'locksmith', 'lamps', 'mall', 'massage', 'motorcycle', 'mobile_phone',
                      'newsagent', 'optician', 'outdoor', 'paint', 'perfumery', 'perfume', 'pet', 'photo', 'second_hand', 
                      'shoes', 'sports', 'stationery', 'tailor', 'tattoo', 'ticket', 'tobacco', 'toys', 'travel_agency',
@@ -69,7 +69,7 @@ layer:
         lodging:
           subclass: ['hotel', 'motel', 'bed_and_breakfast', 'guest_house', 'hostel', 'chalet', 'alpine_hut', 'dormitory']
         ice_cream:
-          subclass: ['chocolate']
+          subclass: ['ice_cream']
         post:
           subclass: ['post_box', 'post_office', 'parcel_locker']
         cafe:

layers/poi/style.json

@@ -22,7 +22,13 @@
             ]
           ]
         },
-        "icon-image": "{subclass}",
+        "icon-image": [
+          "match",
+          ["get", "subclass"],
+          "chocolate",
+          "confectionery",
+          ["get", "subclass"]
+        ],
         "text-field": "{name:latin}\n{name:nonlatin}",
         "visibility": "visible",
         "text-anchor": "top",
@@ -99,7 +105,13 @@
             ]
           ]
         },
-        "icon-image": "{subclass}",
+        "icon-image": [
+          "match",
+          ["get", "subclass"],
+          "chocolate",
+          "confectionery",
+          ["get", "subclass"]
+        ],
         "text-field": "{name:latin}\n{name:nonlatin}",
         "visibility": "visible",
         "text-anchor": "top",