Add a getattr template filter for retrieving an object's attribute.
Review Request #11049 — Created June 20, 2020 and submitted
This filter allows a template to get an attribute of an object without
hard-coding the attribute name up-front. It's useful for cases where you
might be operating off attribute names provided to the template or
computed by another tag.
It's similar to
|getitem:...but uses a
Unit tests passed.
Made use of this in another change.