Basic Authentication/Authorization

[kova98]

There needs to be proper authorization, including roles, for the whole API.

For now, the basic email/user/password auth is enough.

Editing and deleting should be restricted to admins.

• [x] Basic email/user/password auth
• [x] Ensure user has right to edit/delete post

[kova98]

https://stackoverflow.com/questions/61919079/identity-server-4-how-to-add-instagram-login-workflow