Kamal 2: Network changes

kamal-proxy needs a stable hostname for the container that it is routing to. This is so that it can identify and route traffic to the container across restarts.

Using the default bridge network, application containers are assigned IP addresses, but they are not stable across restarts.

So instead, we will create and use a custom network called kamal.

If you have custom requirements for your network, you can create the kamal network yourself before deploying with Kamal, or use a docker-setup hook to configure the network when running kamal setup.

Accessories will also run from within the kamal network.