workflows: Holding Pen authorization

WIP for *basic* authorization in Holding Pen (relying on user being connected to "viewholdingpen" authorization).

* Adds basic "viewholdingpen" authorization to access the Holding Pen.
* Fixes PEP8 issues in local_config.py.

RFC on how to take authorization in Holding Pen to the next level is upcoming.

@kaplun