Label Templates: add IP addresses to the Network variables

[fgiudici]

Add the IPv4 and IPv6 addresses to the NICs template variables.
In particular:

• ${Network/NICs//IPv4Addresses/}
• ${Network/NICs//IPv6Addresses/}
• ${Network/NICs//IPv4Address} # first address from IPv4Addresses
• ${Network/NICs//IPv6Address} # first address from IPv6Addresses
• ${Network/NICs//IPv4Addresses/}
• ${Network/NICs//IPv6Addresses/}
• ${Network/NICs//IPv4Address}
• ${Network/NICs//IPv6Address}

Example:

apiVersion: elemental.cattle.io/v1beta1
kind: MachineRegistration
[...]
  machineInventoryLabels:
    element: fire
    eth1-IPv4: ${Network/NICs/eth1/IPv4Address}               # 10.100.103.144
    eth1-IPv6: ${Network/NICs/eth1/IPv6Address}               # fe80-922a-e5ea-fc77-e503 
    net0-name: ${Network/NICs/0/Name}                              # eth0
    net0-ipv4: ${Network/NICs/0/IPv4Address}                     # 172.21.100.153
    eth0-IPv4-0: ${Network/NICs/eth0/IPv4Addresses/0}    # 10.100.103.144
    eth0-IPv4-1: ${Network/NICs/eth0/IPv4Addresses/1}
    eth0-IPv6-0: ${Network/NICs/eth0/IPv6Addresses/0}    # fe80-922a-e5ea-fc77-e503 
    eth0-IPv6-1: ${Network/NICs/eth0/IPv6Addresses/1}

Part of #855

[kkaempf]

Please add respective tests

[anmazzotti]

Looks good to me, just a few nitpicks.

However I'm worried about the implicit behavior of showing IPv4 before IPv6. Why not both?

My proposal is to explicitly implement *.ipv4 and *.ipv6 annotations.
Makes it also easier to parse the value, so that you don't have to implement a isIPv4? filter for example.

Last but not least, this PR enables this behavior by default, I wonder if this is the desired behavior for everyone or maybe this is worth a new toggle, like a new flag in the MachineRegistration to enable or not reporting of IPs.
If we have the toggle I'd still enable it by default, as this is very nice to have.

[anmazzotti]

Sorry I didn't mean to approve it, pressed the wrong button. :(

[fgiudici]

However I'm worried about the implicit behavior of showing IPv4 before IPv6. Why not both?

My proposal is to explicitly implement *.ipv4 and *.ipv6 annotations. Makes it also easier to parse the value, so that you don't have to implement a isIPv4? filter for example.

Well, have to confess I was mainly looking at the final goal to have an IP address for k3s/RKE2 internal/external address values, and so ended up looking just for one IP address.. but good point, doesn't makes much sense to do this kind of filtering at the annotation level, would make more sense to have ipv4 and ipv6 👍🏼

[fgiudici]

Changed PR to just expose IP addresses as Network variables (on demand).
No more new default annotations.
We now expose IPv4 and IPv6 addresses, updated the PR description accordingly.

[anmazzotti]

Looks good, thank you for the changes!

done, tests added