This is the kind of stuff that's much easier expressed in Python than in
the template code.
API calls removed:
- fetching the user isn't necessary, since we have
pillar.auth.current_user anyway.
- a call for each group the user is member of, since we only used it to
check whether the user has demo access anyway.
I've only done this on the billing page, because there it's important
for debugging purposes to know which URL was actually checked to obtain
the subscription expiry information.
A 403 indicates the session isn't valid any more, and a window reload will
fix that (either by automatically logging in via Blender ID or by
providing a login prompt).
