Fix refresh button functionality for network printing

plugins/UM3NetworkPrinting/src/Network/LocalClusterOutputDeviceManager.py

@@ -57,10 +57,14 @@ class LocalClusterOutputDeviceManager:
     ## Stop network discovery and clean up discovered devices.
     def stop(self) -> None:
         self._zero_conf_client.stop()
-        # Cleanup all manual devices.
         for instance_name in list(self._discovered_devices):
             self._onDiscoveredDeviceRemoved(instance_name)
 
+    ## Restart discovery on the local network.
+    def startDiscovery(self):
+        self.stop()
+        self.start()
+
     ## Add a networked printer manually by address.
     def addManualDevice(self, address: str, callback: Optional[Callable[[bool, str], None]] = None) -> None:
         api_client = ClusterApiClient(address, lambda error: print(error))

plugins/UM3NetworkPrinting/src/UM3OutputDevicePlugin.py

@@ -37,6 +37,10 @@ class UM3OutputDevicePlugin(OutputDevicePlugin):
         self._network_output_device_manager.stop()
         self._cloud_output_device_manager.stop()
 
+    ## Restart network discovery.
+    def startDiscovery(self) -> None:
+        self._network_output_device_manager.startDiscovery()
+
     ## Force refreshing the network connections.
     def refreshConnections(self) -> None:
         self._network_output_device_manager.refreshConnections()