host: wait for view in Edit host step (SatelliteQE#1362)

`EditHost` step now waits for the view to be displayed.

Needed for an edge case, when editing a host with empty values, i.e.,
`host.update(client.hostname, {})`,
is too fast and the view is not yet fully loaded.

airgun/entities/host.py

@@ -464,6 +464,7 @@ def step(self, *args, **kwargs):
         entity_name = kwargs.get('entity_name')
         self.parent.search(entity_name)
         self.parent.table.row(name=entity_name)['Actions'].widget.fill('Edit')
+        self.view.wait_displayed()
 
 
 @navigator.register(HostEntity, 'Select Action')