[mayfly] Support custom ClusterRole rules through values.yaml

[qjoly]

Description

This PR enhances the Mayfly Helm chart by adding the capability to customize the ClusterRole rules directly through the values.yaml file. This provides better flexibility for users to define their own RBAC permissions without having to modify the template files.

I've seen that it's possible to limit the resources that the operator will manage, but it's probably better to restrict rights directly from the Kubernetes RBAC by editing the clusterRole.

Example Usage

Users can now customize the ClusterRole permissions by adding their specific rules in the values.yaml file:

clusterRole:
  rules:
    - apiGroups: ["apps"]
      resources: ["deployments"]
      verbs: ["get", "list", "watch", "create", "update", "delete"]