chore: Implement better Price abstraction for Digital Ocean server provider

lib/logic/cubit/provider_volumes/provider_volume_cubit.dart

@@ -27,7 +27,7 @@ class ApiProviderVolumeCubit
   }
 
   Future<Price?> getPricePerGb() async =>
-      ProvidersController.currentServerProvider!.getPricePerGb();
+      (await ProvidersController.currentServerProvider!.getPricePerGb()).data;
 
   Future<void> refresh() async {
     emit(const ApiProviderVolumeState([], LoadingStatus.refreshing, false));

lib/logic/providers/server_providers/digital_ocean.dart

@@ -779,9 +779,12 @@ class DigitalOceanServerProvider extends ServerProvider {
   /// Hardcoded on their documentation and there is no pricing API at all
   /// Probably we should scrap the doc page manually
   @override
-  Future<Price?> getPricePerGb() async => Price(
-        value: 0.10,
-        currency: 'USD',
+  Future<GenericResult<Price?>> getPricePerGb() async => GenericResult(
+        success: true,
+        data: Price(
+          value: 0.10,
+          currency: 'USD',
+        ),
       );
 
   @override