add check for identifiers.org redirect

[satra]

given the issue we had with identifiers. perhaps we can add a check for redirect in creating these webshots.

[yarikoptic]

what extra benefit that would be on top of dandi-cli AFAIK already testing that we are getting redirected properly by identifiers.org? As long as redirected - webshots shouldn't differ, right?

[satra]

perhaps being paranoid but mostly at this stage just making sure that pathway is working for all existing dandisets.