Add role to install clatd

[RealOrangeOne]

Summary

clatd is a magical ✨ tool I don't quite understand which allows our VMs to have outbound IPv4 connectivity, without needing a dedicated address. This avoids the need to have an IPv4 address for the VM. The tool was recommended by Mythic, who also helped with the configuration.

Specifically, this is needed for the Discord bot, since Discord's API is known to be unhappy with IPv6-only connections.

I've intentionally leant on the Makefile in the project, rather than duplicating the dependencies, to allow for simpler upgrades in future.

Code review

Testing

• applied the configuration locally
• manually validated the new behaviour

Links

The configuration itself has already been tested on the server.

[sedders123]

Added a couple of comment suggestions with my understanding of things. I propose we merge so that the Discord bot is unblocked and add additional comments or tweaks in a follow PR as required

[PeterJCLaw]

@RealOrangeOne was it intentional to remove the changes we'd added last night (mostly around documenting how this works)?

[RealOrangeOne]

Yes. Much of what was there was either documenting how Ansible and clatd work, or was wrong. I incorperated the relevant changes into my commit, notably moving them to the role's README rather than keeping them in the host_vars file.

[PeterJCLaw]

Thanks for persevering with this 👍