http remote: check and handle properly access denied and other HTTP codes

[shcheklein]

Looks like when HTTP remote can't return an object and returns access denied we consider it the same way as 404 and don't even mention this to user.

[efiop]

@shcheklein Are you talking about dvc pull from http remote? Or something else?

[shcheklein]

@efiop yep, it was dvc pull/dvc fetch.