support ipv6 connectivity for the bridge network

[sinisterstumble]

It seems there is simply no way to setup ipv6 connectivity for the default nomad bridge.

Thank you!

[jrasell]

Hi @markmartirosian and thanks for raising this feature request.

[gulducat]

Hello! When #23882 is shipped with Nomad 1.9, IPv6 may be enabled on the Nomad bridge network mode by setting an IPv6 subnet in the client agent config, e.g.:

client {
  enabled = true

  bridge_network_subnet_ipv6 = "fd00:a110:c8::/116"
}