Fix default accessory icon

Author: wangwillian0

lib/accessory/accessory_model.dart

@@ -67,7 +67,7 @@ class Accessory {
     this.isActive = false,
     this.isDeployed = false,
     LatLng? lastLocation,
-    String icon = 'mappin',
+    String icon = 'push_pin',
     this.color = Colors.grey,
     this.usesDerivation = false,
     this.symmetricKey,

lib/item_management/item_file_import.dart

@@ -139,7 +139,7 @@ class _ItemFileImportState extends State<ItemFileImport> {
       color = Color.fromRGBO(red, green, blue, opacity);
     }
 
-    String icon = 'mappin';
+    String icon = 'push_pin';
     if (AccessoryIconModel.icons.contains(accessoryDTO.icon)) {
       icon = accessoryDTO.icon;
     }