dls-aravis does not work in a devcontainer

[gilesknap]

Because the devcontainer relies on directly mounting a config folder into /epics/ioc/config the two aravis ioc instances in this repo do not work. When deploying to the cluster, helm gets a look in to render a nice ioc.yaml for these instances but no such thing exists in the devcontainer.

Proposal:
I need some kind of external process to render the ioc.yaml using helm template into a separate folder then symlink that into epics/ioc/config. This would have to be a two stage process, render outside and then symlink inside in the usual way with ibek dev instance

@coretl @marcelldls it's worth keeping this in mind when we think about cool ways to use helm in our ioc instances. I'm kind of OK with this as helm template is exactly what argocd uses so it should always be possible to make the ioc.yaml file somehow.