Show IPv6 adoption

[J0WI]

Show statistics, whether the data has been submitted over IPv6 or IPv4.

[J0WI]

Looks like incoming.telemetry.mozilla.org does not even support IPv6. IPV4_AND_IPV6_ADDRESS_CONNECTIVITY is the only existing data I found about IPv6, but it's not very useful for this case.

It would be quite interesting to have these stats.

[openjck]

Thanks for the suggestion. Copying @fbertsch who works on the data pipeline.