Chore: Add user service method GetByLogin (#53204)

* Add wrapper around sqlstore method GetUserByLogin

* Use new method from user service

* Fix lint

* Fix lint 2

* fix middleware basic auth test

* Fix grafana login returning a user by login

* Remove GetUserByLogin from store interface

* Merge commit

pkg/services/user/user.go

@@ -8,4 +8,5 @@ type Service interface {
 	Create(context.Context, *CreateUserCommand) (*User, error)
 	Delete(context.Context, *DeleteUserCommand) error
 	GetByID(context.Context, *GetUserByIDQuery) (*User, error)
+	GetByLogin(context.Context, *GetUserByLoginQuery) (*User, error)
 }