Fix showing progress from other sessions

Because `client_id` was missing from ths `progress_state` message, it
was being sent to all connected sessions. This technically meant that if
someone had a graph with the same nodes, they would see the progress
updates for others.

Also added a test to prevent reoccurance and moved the tests around to
make CI easier to hook up.

tests/execution/extra_model_paths.yaml

@@ -0,0 +1,4 @@
+# Config for testing nodes
+testing:
+    custom_nodes: testing_nodes
+