Add wifi-based geolocation, where available

[bwarden]

Is your feature request related to a problem? Please describe.
I have a couple of portable nodes (GL-AR750). I'd like to be able to update their location as automatically as possible.

Describe the solution you'd like
Scan for nearby WiFi access points and submit them to a free, public geolocation service to get an approximate location (https://beacondb.net/).

This will only work if:

• the node has access to the internet
• the node has an additional radio not used for AREDN that we can use to scan
• Other wifi APs are actually nearby to scan
• The geolocation service is online
• The geolocation service has mapping data for the current area

The beacondb service will fall back to public IP geolocation, with a city-sized area of precision

Describe alternatives you've considered

• Adding a USB (or I2C) GPS puck
  • requires extra hardware purchase
  • requires view of the sky
• Using browser-based geolocation
  • requires connecting a browser to the node
  • requires that the device with a browser can successfully complete geolocation via a similar service

Additional context
This is just an idea to provide a supplemental service to geolocate a node. I don't intend to replace anything; just to make something new available.