Add persistentvolume PV/PVC support for chartmuseum

**Is your feature request related to a problem? Please describe.**
A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
Currently chartmuseum stores all charts locally, in it's container filesystem. This makes it a stateful service. We require a PV/PVC to store the staged charts so that they persist across pod restarts and also allow us to scale replicas for chartmuseum in prod use-cases.

**Describe the solution you'd like**
A clear and concise description of what you want to happen.
Add support for PV/PVC for chartmuseum (it comes with support for minio which could be leveraged for this)

**Describe alternatives you've considered**
A clear and concise description of any alternative solutions or features you've considered.

**Additional context**
Add any other context or screenshots about the feature request here.

[ ] KinD cluster
[ ] Public Cloud