Authorize users using an Almanna entity. Requires additional config to work: * entity_type: mapping to the string representation of the GLib type of the entity. Example: ExampleApp.Model.DB.User would be ExampleAppModelDBUser. Optional config: * password_type: Type of password obfuscation/hashing in place. Defaults to a SHA1 PasswordType, but can be changed with password_type and that password type's associated configuration. * id_field: Defaults to first primary key property or "id" * username_field: Defaults to username * password_field: Defaults to password