Add ability to create custom role in Portainer based on a Kubernetes Cluster Role

[samdulam]

Add ability to create a Custom Role in Portainer based on a pre-exisiting ClusterRole / Role in a Kubernetes Cluster.
Use Case: Need more fine grain control on top of what Portainer already provides in terms of Roles.

We could simply get use input for

• Name
• Scope (Cluster/Global or Namespace)
• Select a ClusterRole/Role from a list of Roles (retrieved from all kubernetes clusters (endpoints)) eg: <endpointname>:<rolename>

Portainer could then replicate the role to all other clusters, create the custom role and role bindings as normal.