Feature: Add customisable icons in topology (#193)

* [up] add config for custom images, better js

* [up] use bundler to bundle js

* [fix] remove domcontentloaded since defer is used

* [fix] formatting with black

* [fix] images drf api

* [up] add support for custom icons on additional roles: power panel, power feed, circuit

* [up] optimize topology generation by using `_id` when trying to access pk of related object

* [fix] kebab case instead of slugification

* [fix] use empty queryset in api views & change coord save logic

netbox_topology_views/api/serializers.py

@@ -1,12 +1,22 @@
+from dcim.models import Device, DeviceRole
 from rest_framework.serializers import ModelSerializer
 
-from dcim.models import DeviceRole, Device
-from extras.models import Tag
+from netbox_topology_views.models import RoleImage
 
 
 class TopologyDummySerializer(ModelSerializer):
-
     class Meta:
         model = Device
-        fields = ('id', 'name')
-        
+        fields = ("id", "name")
+
+
+class RoleImageSerializer(ModelSerializer):
+    class Meta:
+        model = RoleImage
+        fields = ("role", "image")
+
+
+class DeviceRoleSerializer(ModelSerializer):
+    class Meta:
+        model = DeviceRole
+        fields = ("name", "slug", "color", "vm_role", "description")