[node] add params validation

Fixes for: https://github.com/paritytech/helm-charts/issues/349

Changes:

Deployment will fail if the node keys or ID are defined multiple times.

Example of error:

# examples/local-rococo/bootnode.yaml
node:
  customNodeKey: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
  persistGeneratedNodeKey: true

helm upgrade --install bootnode . -f examples/local-rococo/bootnode.yaml
Error: UPGRADE FAILED: execution error at (node/templates/statefulset.yaml:7:3): Error: Only one of [ .Values.node.persistGeneratedNodeKey .Values.node.customNodeKey] can be set.

Fix: Remove either .Values.node.persistGeneratedNodeKey or .Values.node.customNodeKey from the custom values file (e.g., -f examples/local-rococo/bootnode.yaml).

paritytech / helm-charts

[node] add params validation #353