Redirect to original URL after login flow

[sergiimk]

Currently after logging in the user is always redirected to the home page.

This is inconvenient when you have tabs that are open for a long time and your session expires - you lose for which dataset the tab was opened and have to navigate back to it again.

This feature request is to preserve the current URL as callback_url parameter of the auth flow which when present at the end of login flow will redirect the user to the same place they were on before logging in.