Topology button in Site View (#220)

* Topology button in Site View

* Add mdi icons to Topology and Close Buttons

* Fix buttons tag and class

* fixed drag & site filter

Co-authored-by: Mattijs Vanhaverbeke <mattijs.vanhaverbeke@ebo-enterprises.com>

netbox_topology_views/static_dev/js/home.js

@@ -70,8 +70,9 @@ const coordSaveCheckbox = document.querySelector('#id_save_coords')
     graph.fit()
 
     graph.on('dragEnd', (params) => {
+        if (coordSaveCheckbox == null) return
         if (!coordSaveCheckbox.checked) return
-
+        
         Promise.allSettled(
             Object.entries(graph.getPositions(params.nodes)).map(
                 async ([nodeId, nodePosition]) => {