Created folder structure for coursemanagementsystem includes layers api,services,database layer

Created folder structure for course-management-system which includes i.e. three layers API, Services, Database Layer In the Api layer we have included controllers, filters, Middlewares, DI configurations & in the service layer DI configurations, DTO, Implementations, Interfaces & mapping profile included and also the Database layer we have included Databasecontext, DI configurations, Entities, Implementations, Interfaces