#20875 fix updating of denormalized fields (_site, _location, _rack) for component models

[arthanson]

Fixes: #20875

Several cases were previously missed:

• when creating a device from a device template, components are instantiated from the device-template and the denormalized fields are never getting updated.
• when doing bulk operations the signal was also not getting ran so they weren't updated.

Also checked the API and it looks like the API and this should also affect those. Bulk updates on the API do serializer.save() on each object which will cause the signal handler to run.

Since this is used in both bulk operations and signal handling I used a common routine as I wanted the updates in one place in-case we ever add values or need to modify the logic any.