UserClaim: Add StorageAccessMode

[camrossi]

Chart type
Memgraph Standalone

What happened?
I am creating a K8s HELM chart for an application that will periodically pull a relationship database backup, convert it into CSV and load it into Memgraph with LOAD CSV commands.

There are 2 main components:

• DB Conversion POD
• Memgraph

Since the CSV needs to reside on a PVC that is directly attached to Memgraph it makes sense to be able to have the UserClaim as RWX so that the DB Conversion POD and Memgraph can share the same PVC.

I think this would be useful in general for the UserClaim PVC