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/static_dev/js/toast.js

@@ -0,0 +1,18 @@
+export const toast = {
+    success: (message) => {
+        const el = document.querySelector('#topology-plugin-success-toast')
+        if (!el) return console.error('Could not find toast component!')
+        const content = el.querySelector('span')
+        content.textContent = message
+        const toast = new window.Toast(el)
+        toast.show()
+    },
+    error: (message) => {
+        const el = document.querySelector('#topology-plugin-error-toast')
+        if (!el) return console.error('Could not find toast component!')
+        const content = el.querySelector('span')
+        content.textContent = message
+        const toast = new window.Toast(el)
+        toast.show()
+    }
+}