WiFi Health Tool

[bplattenburg]

Add a new tool to check the health of the local WiFi network. This includes both a UI and a HealthMetricProvider implementation. We should be able to leverage Apple's NEHotspotNetwork and related code to get the data.

This tool gets the values for first whether WiFi is connected, and if it is the ssid, bssid (the specific access point, useful to see if a single AP is overloaded), and signalStrength (based on rssi but not synonymous, see https://developer.apple.com/documentation/networkextension/nehotspotnetwork/1618923-signalstrength) of the connected network.

The UI simply displays all these values

The HealthMetricProvider always provides the same connected boolean, and if connected the ssid, bssid, and signalStrength as the UI.

Its 'healthy boolean is somewhat configurable:

• if the device is not connected to WiFi it is always unhealthy
• If the ssid does not match an optional configuration value of "expectedSSID", it is unhealthy (covers enterprise scenarios where the customer wants to validate the devices are on the correct WiFi with the other peers).
• If the signalStrength is below an optional configured minimum value.