External authentication doesn't redirect correctly

See https://github.com/oaeproject/3akai-ux/issues/3198. We should probably try to come up with a way in which the redirect URL (e.g. https://marist.oaeproject.org/accessdenied?url=/content/marist/ektQDO2oz) is followed after signing in through an external authentication provider.

Description: When I upload a file to my library and share it with another user I sometimes then send the user the URL to access the file directly in OAE. If the user is already signed-in and they go to the URL they get to the file directly. If the user is not already signed-in and they go to the URL they first need to sign-in but upon doing so they are directed to their "recent activity" page. This can be confusing as they have to know to go to their library to find the file.

IMPORTANT > I think this may be an issue with how our CAS service redirects users once they authenticate as it may be re-directing to the main OAE URL rather than back to the URL from which the user "came". If this is what other think is the issue, it would be useful to see if you could assign this ticket to Uday as a test of how we might handle such issues moving forward.

How to Replicate the Issue:
(1) Upload a file to your library and make it private.
(2) Copy the URL to the file page in OAE.
(3) Open up a different browser and make sure you are not authenticated into OAE
(4) Copy the URL into the browser and attempt to access the file in OAE.
(5) When you get the 401 error, sign into OAE.
(6) You should find that you are brought to your activity stream instead of the OAE page for the file.
If you attempt these steps when you are already signed-in you'll get directly to the OAE page.

Browsers: I've replicated this with Firefox and Chrome.