Add broker.py to this repository?

[maurerle]

The broker currently lives in https://github.com/ffac/ff-supernode/blob/main/playbooks/roles/ff.wgbroker/templates/broker.py
But as it basically touches the wireguard keys as well, it might make sense to add this to this repository as well.

So that we have a single repository with the utilities which take care about key handling.

On the other hand, there is still https://github.com/maurerle/ff-supernode/blob/main/playbooks/roles/ff.mesh_wireguard/tasks/netlink.yml#L33 which configures the side which manages the keys on the supernode through this repository:
https://github.com/freifunkh/wireguard-vxlan-glue