ipv6 connectivity -- managing NDP entries

/kind feature

**Description**

Podman 4.0 has added support for ipv6 static addresses (really appreciating the perf improvements with netavark, btw). Podman also has facilities for routing traffic to containers (e.g. managing firewall rules). With this in mind, it could be nice if Podman also took the step of ensuring ipv6 connectivity through managing the host's NDP table.

Linux has some support for responding to NDP requests, but this must manually set with iproute2 per address and not an entire subnet. It is therefore more practical to run a daemon ([ndppd](https://github.com/DanielAdolfsson/ndppd), [ndpresponder](https://github.com/yoursunny/ndpresponder)) to do this mapping dynamically. Could Podman remove the need for this extra dependency by managing the host's NDP table to automatically ensure connectivity to containers?