Fixes #19056 – Add Device filtering by Location slug (#19180)

* feat(dcim): Add filter by location slug for Device

Introduces a TreeNodeMultipleChoiceFilter for filtering locations by
slug. Enhances filtering flexibility in the Device model by supporting
both ID and slug lookups.

Fixes #19056

* feat(dcim): Add Device filtering by location slug in tests

Extend test cases to include filtering by location slug. Ensures the
FilterSet works correctly with slug-based queries for locations.

Fixes #19056

netbox/dcim/tests/test_filtersets.py

@@ -2561,6 +2561,8 @@ class DeviceTestCase(TestCase, ChangeLoggedFilterSetTests):
         locations = Location.objects.all()[:2]
         params = {'location_id': [locations[0].pk, locations[1].pk]}
         self.assertEqual(self.filterset(params, self.queryset).qs.count(), 2)
+        params = {'location': [locations[0].slug, locations[1].slug]}
+        self.assertEqual(self.filterset(params, self.queryset).qs.count(), 2)
 
     def test_rack(self):
         racks = Rack.objects.all()[:2]