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

netbox/dcim/filtersets.py

@@ -1057,6 +1057,13 @@ class DeviceFilterSet(
         lookup_expr='in',
         label=_('Location (ID)'),
     )
+    location = TreeNodeMultipleChoiceFilter(
+        queryset=Location.objects.all(),
+        field_name='location',
+        lookup_expr='in',
+        to_field_name='slug',
+        label=_('Location (slug)'),
+    )
     rack_id = django_filters.ModelMultipleChoiceFilter(
         field_name='rack',
         queryset=Rack.objects.all(),