Add validators and services for Product Galleries and Product Tags

- Implemented Create, Delete, Get, and Update validators for Product Galleries.
- Added Create, Delete, Get, and Update validators for Product Tags.
- Created service classes for handling Discount Categories, Discount Orders, Discount Products, Discount Shopping Cart, Product Categories, Product Galleries, and Product Tags.
- Each service class integrates with CQRS for command and query handling.
- Established mapping profiles for Product Galleries.

src/CMSMicroservice.Application/UserCartsCQ/Queries/GetUserCarts/GetUserCartsQueryHandler.cs

@@ -11,12 +11,12 @@ public class GetUserCartsQueryHandler : IRequestHandler<GetUserCartsQuery, GetUs
     public async Task<GetUserCartsResponseDto> Handle(GetUserCartsQuery request,
         CancellationToken cancellationToken)
     {
-        var response = await _context.UserCartss
+        var response = await _context.UserCarts
             .AsNoTracking()
             .Where(x => x.Id == request.Id)
             .ProjectToType<GetUserCartsResponseDto>()
             .FirstOrDefaultAsync(cancellationToken);
 
-        return response ?? throw new NotFoundException(nameof(UserCarts), request.Id);
+        return response ?? throw new NotFoundException(nameof(UserCart), request.Id);
     }
 }