Use NetworkLinkService instead of Moat for the internet test
Spun out from #42605 (comment 3128884).
Instead of contacting Moat to test the internet, which would require user permission as per our design docs, we can use the nsINetworkLinkService API for:
- Testing the internet connection in
TorConnect. - Showing the internet connection state in
about:preferences#connection.
As a result, we can also drop the "Test" button from about:preferences#connection and just make it a live status.
I'm guessing Android doesn't have an existing "Test" button anywhere.
Looping in UX for them to be aware, but this shouldn't need any input if it goes smoothly.