Feature: Authentication and authorization API

- [ ] Controllers
    - [ ] [LoginController](https://github.com/Caity-app/Api/blob/main/Controllers/LoginController.cs)
    - [ ] [RegisterController](https://github.com/Caity-app/Api/blob/main/Controllers/RegisterController.cs)
- [ ] Services
    - [ ] MemberRegistration
    - [ ] MemberAuthentication
    - [ ] MemberAuthorization