Refined network management (#1672)

This PR implements several refinements to the way that NetworkManager
controls the network interface.

- The monitor detects and logs changes to the network address
- The monitor detects and logs changes to the connection and will
reinitialize the connection if needed
- Remove NetworkInterface.java class, which wasn't used anywhere
- Use java.net.NetworkInterface to get IP addresses for any interface
(device)
- Adds a metric for the current IP address (address on the currently
selected interface)

photon-client/src/types/SettingTypes.ts

@@ -23,6 +23,7 @@ export interface MetricData {
   cpuUptime?: string;
   diskUtilPct?: string;
   npuUsage?: string;
+  ipAddress?: string;
 }
 
 export enum NetworkConnectionType {