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/GlobalUsings.cs

@@ -1,6 +1,7 @@
 global using MediatR;
 global using FluentValidation;
 global using Mapster;
+global using Microsoft.Extensions.Logging;
 
 global using CMSMicroservice.Domain.Entities;
 global using CMSMicroservice.Domain.Entities.Club;