settings: Allow to toggle mobile data

This adds a status page to the wwan quick setting allowing to toggle mobile data. The way we pick the mobile data connection when enabling is heuristic so I'm open to suggestions on how to improve this. We also don't toggle any autoconnect settings on those connections, should we?

This MR cleans up some bits in around wifi status page too so @arun-mani-j maybe you can check if that looks sane.

Closes: #691 (closed)

Toggling mobile data together with hotspot (!1379) are the last two bits that make me resort to the settings app ever so often. Another bit could be #1061 (vpn selection).