Add MassData API with CQRS, repository, and DbContext

Introduce MassData feature with new API endpoints for querying and upserting records by customer name. Add DTOs, AutoMapper profile, MediatR CQRS handlers, repository pattern, and MassDataDbContext. Register new services in DI and add MassDataConnection to configuration. Upsert uses stored procedure. Enables full CRUD for Massdata via dedicated API.

DbFirst.Application/MassData/MassDataProfile.cs

@@ -0,0 +1,12 @@
+using AutoMapper;
+using DbFirst.Domain.Entities;
+
+namespace DbFirst.Application.MassData;
+
+public class MassDataProfile : Profile
+{
+    public MassDataProfile()
+    {
+        CreateMap<Massdata, MassDataReadDto>();
+    }
+}