OAuth2 Integration for Auth Server

[aligoren]

Currently, we have custom logic in auth service. This isn't a standart. If we implement OAuth2 feature, it would be nice to manage clients who connect to the auth service.

These are resources. We can use these resources to understand how OAuth2 works and we can implement it :)

https://www.sohamkamani.com/golang/oauth/

https://oauth.net/code/go/

https://tutorialedge.net/golang/go-oauth2-tutorial/

https://itnext.io/getting-started-with-oauth2-in-go-1c692420e03

https://go-oauth2.github.io/

https://www.loginradius.com/blog/engineering/google-authentication-with-golang-and-goth/

https://pepa.holla.cz/2020/12/07/golang-fiberv2-oauth2/

https://github.com/gofiber/fiber/issues/292