Filter stock-takes based on active state

[Thizizmyname]

We have a huge amount of products in our database and many of them we haven't had in stock for a long time. These product should be able to filter out from a stock-take to make it easier to handle our inventory.

Every product already have an "active" checkmark so should be easy to implement.

The filtering could be done in the "initiate_stocktaking" method in:
foobar-api/src/shop/api.py

This could also be expanded to if a product has been zero between two stock-takes and the inventory of the product has not changed in the time period, it could be auto-assigned to inactive.