Make workspace PVC's Access mode configurable

[Ex4amp1e]

Description

Current PVC spec has AccessModes hardcoded to ReadWriteOnce value.

It may be helpful to configure AccessModes parameter and to require RWX access from the storage provider and rely, that there can't be a situation, where workspaces are no longer properly distributed across the nodes.

[AObuchow]

@amisevsk do you have any thoughts on this?

One thing that comes to mind is whether this should be configurable at the devworkspace level and DWOC level, or just the DWOC. Since the storage class is exclusively configured by the DWOC, I would imagine this should be a DWOC option.