Feat: provide longhorn PVCs

[maybeanerd]

It seems that longhorn can be used even with a single node that provides storage.
I want to install longhorn on Argo with a chart
https://longhorn.io/docs/1.9.1/deploy/install/install-with-argocd/

And then try using it e.g. for the immich test app. If it works well, I want to migrate all NFS volumes to longhorn.

[maybeanerd]

longhorn is running ✅
it allows only to use cube03 raid hdd storage ✅
it provides pvcs with PVs ✅
it fails to provide the mounst to e.g. immich-testing on cube04 🚫

[maybeanerd]

We might be able to check the setup and install missing parts using the CLI
https://longhorn.io/docs/1.9.1/deploy/install/#longhorn-command-line-tool

[maybeanerd]

longhorn now seems to be able to mount the PVs , without us doing changes (we did have some longhron updates in the meantime)

Keeping this issue open until the first service successfully used (as in stored & retrieved data) this way