Make name field for EV chargers optional, closes #688

and instead, promote the usage of the `brand` field

also add `network` field (used on 15% of chargers) and remove `branch` field (which is currently not used in practice)

data/presets/amenity/charging_station.json

@@ -1,7 +1,7 @@
 {
     "icon": "fas-charging-station",
     "fields": [
-        "name",
+        "brand",
         "operator",
         "capacity",
         "access_simple",
@@ -10,11 +10,10 @@
         "charge_fee"
     ],
     "moreFields": [
-        "branch_brand",
-        "brand",
         "covered",
         "level",
-        "manufacturer"
+        "manufacturer",
+        "network"
     ],
     "geometry": [
         "point",