Add submenu for GameResource

[bub-bl]

Add a way to add few game resource in the same category

[GameResource(Category = "MyCategory", ...)] does not working

[bub-bl]

@garrynewman

I can't create a pull request with code for this fix on https://github.com/sboxgame This code fix this issue:

• Go in file \sbox\addons\tools\code\CreateAsset.cs
• Go at line 84

• Replace the following code:

                      menu.AddOption( $"New {gameResource.Name}..", gameResource.Icon, () =>
          {
              var fd = new FileDialog( null );
              fd.Title = $"Create {gameResource.Name}";
              fd.Directory = folder.FullName;
              fd.DefaultSuffix = $".{gameResource.Extension}";
              fd.SelectFile( $"untitled.{gameResource.Extension}" );
              fd.SetFindFile();
              fd.SetModeSave();
              fd.SetNameFilter( $"{gameResource.Name} (*.{gameResource.Extension})" );
  
              if ( !fd.Execute() )
                  return;
  
              CreateNew( fd.SelectedFile );
  
          } );

• With this code

                      // Create sub menu from category propery if is not empty
          var subMenu = string.IsNullOrWhiteSpace(gameResource.Category)
              ? menu
              : menu.FindOrCreateMenu(gameResource.Category);
  
          subMenu.AddOption( $"New {gameResource.Name}..", gameResource.Icon, () =>
          {
              var fd = new FileDialog( null );
              fd.Title = $"Create {gameResource.Name}";
              fd.Directory = folder.FullName;
              fd.DefaultSuffix = $".{gameResource.Extension}";
              fd.SelectFile( $"untitled.{gameResource.Extension}" );
              fd.SetFindFile();
              fd.SetModeSave();
              fd.SetNameFilter( $"{gameResource.Name} (*.{gameResource.Extension})" );
  
              if ( !fd.Execute() )
                  return;
  
              CreateNew( fd.SelectedFile );
          } );