Evaluate sub-resource storage / APIs

[olzemal]

Kubernetes sub-resources are useful for example when:

• only partially updating a resource
• providing action orientated apis / verbs (e.g. restart)
• extending / specifying advanced RBAC rules (e.g. only granting access to status)

AC:

• evaluate if sub-resources are something we want to implement in e.g. Solar / ARC
• evaluate how to implement sub-resources for extension apiservers (in a generic way for reusability)