Refactoring result codes (#731)

* refactoring result codes

- Add a main enum who can handle some orphalin result codes and the default `ResultCode.Success` one.
- Add sub-enum by services when it's needed.
- Remove some empty line.
- Recast all service calls to ResultCode.
- Remove some unneeded static declaration.
- Delete unused `NvHelper` class.

* NvResult is back

* Fix

Ryujinx.HLE/HOS/Services/Am/IWindowController.cs

@@ -8,22 +8,22 @@ namespace Ryujinx.HLE.HOS.Services.Am
 
         [Command(1)]
         // GetAppletResourceUserId() -> nn::applet::AppletResourceUserId
-        public long GetAppletResourceUserId(ServiceCtx context)
+        public ResultCode GetAppletResourceUserId(ServiceCtx context)
         {
             Logger.PrintStub(LogClass.ServiceAm);
 
             context.ResponseData.Write(0L);
 
-            return 0;
+            return ResultCode.Success;
         }
 
         [Command(10)]
         // AcquireForegroundRights()
-        public long AcquireForegroundRights(ServiceCtx context)
+        public ResultCode AcquireForegroundRights(ServiceCtx context)
         {
             Logger.PrintStub(LogClass.ServiceAm);
 
-            return 0;
+            return ResultCode.Success;
         }
     }
 }