This uses the new names introduced in edx-django-utils
3.8.0 (edx/edx-django-utils#59), which we're already using, as
well as updating a few other locations where we incorrectly refer
to New Relic custom metrics instead of custom attributes.
Includes a couple of unrelated lint fixes in a file I modified.
* includes ADR for Monitoring by Code Owner
* add monitoring middleware to add the following custom metrics:
- code_owner: The owning team mapped to the current view.
- code_owner_mapping_error: If there are any errors when trying to
perform the mapping.
- view_func_module: The __module__ of the view_func, which can
be used to find missing mappings.
* add script to generate `settings.CODE_OWNER_MAPPINGS` from
a csv file.
ARCHBOM-1244
