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.WebApi/appsettings.json

@@ -1,6 +1,5 @@
 {
   "UseRealPaymentGateway": false,
-  "PaymentProvider": "BankMellat",
   "JwtSecurityKey": "TvlZVx5TJaHs8e9HgUdGzhGP2CIidoI444nAj+8+g7c=",
   "JwtIssuer": "https://localhost",
   "JwtAudience": "https://localhost",
@@ -45,12 +44,6 @@
     "BaseUrl": "https://api.daya.ir",
     "ApiKey": "YOUR_DAYA_API_KEY"
   },
-  "BankMellat": {
-    "ServiceUrl": "https://bpm.shaparak.ir/pgwchannel/services/pgw",
-    "TerminalId": "YOUR_TERMINAL_ID",
-    "Username": "YOUR_USERNAME",
-    "Password": "YOUR_PASSWORD"
-  },
   "AllowedHosts": "*",
   "Kestrel": {
     "EndpointDefaults": {