Implement nebula v1.10/cert v2

[nbrownus]

This PR adds support for nebula v1.10/cert v2 (ipv6 overlay, multiple vpn networks) in the UI and in vpn networking.

Main things to note:

• Active tunnels view shows the name of the certificate instead of a vpn address now.
• Moved from listHostmaps to listIndexes to fetch the active hostmap since 1 tunnel (index) can be 1 or more "hosts" thanks to multiple vpn networks in certs. We can still have multiple tunnels to a host (name) but it's far less likely.

TODO:

• Pin against an actual released version of dnapi, it's currently targeting a branch.
• Determine if we want to allow dual v1/v2 certificate configurations, currently only allowing a single cert as before, fix the fallout based on the decision.
• Determine if we want nebula to output a flattened json representation of v1/v2 certificates, fix the fallout based on the decision.
• We should likely display each vpn/unsafe network in its own widget that better supports copying the entire value/making the content scrollable on a single line.
• There may be a problem with overly long certificate names being displayed in the active tunnel list, need to test.