Add "empty" API filter on custom fields of type date

[SaschaSchwarzK]

NetBox version

v4.1.8

Feature type

New functionality

Triage priority

I volunteer to perform this work (if approved)

Proposed functionality

When requesting data from API enable filtering for custom fields of type date for objects where the field is none.
example API call:
https://demo.netbox.dev/api/dcim/device-types/?cf_EOL_DATE__empty=true/

Use case

There is currently no way to filter objects by custom fields of type date to get only the objects where is no value set.
This functionality would improve the usability as it avoid to download all object and filter them in external code.

Database changes

none

External dependencies

none