Add IPv6 support

[joachimtingvold]

Is your feature request related to a problem? Please describe.
Can't run the device on IPv6-only networks.

Describe the solution you'd like
Add IPv6 support (SLAAC + Static as a minimum, DHCPv6 as a bonus).

Describe alternatives you've considered
N/A

Additional context
Services that should support IPv6: web service, DNS, NTP and Zigbee socket connection. Maybe also the firmware update parts (but that requires the external services to support IPv6 as well, so maybe that would have to be a future thing).

[SAOPP]

Current hardware board revision is not supported IPv6.

IPv6 support will be implemented in future releases.

[xyzroe]

It's not a hardware issue.

to implement IPv6 support we need to change esp32-platform, that is using in the firmware, to a new version.

[SAOPP]

So I misunderstood u from the start.