Add support for the "node.roles" setting

[barkbay]

With Elasticsearch 7.9 the individual settings node.* are deprecated in favor of a node.roles setting.

Related ES PR:

• main branch: Introduce node.roles setting elasticsearch#54998
• For 7.x Introduce node.roles setting elasticsearch#58512

We need to update several places in the code where ECK relies on the node.* attributes to detect the nature of a node:

• Validation function
• When we set the labels on the Pods

Note that it is not possible for the user to use both the legacy method and the new one:

e.g.

config:
node.master: true
node.roles:
    - data

produces the following error:

java.lang.IllegalArgumentException: can not explicitly configure node roles and use legacy role setting [node.master]=[true]

See https://github.com/elastic/elasticsearch/blob/master/server/src/main/java/org/elasticsearch/cluster/node/DiscoveryNode.java#L57 for implementation details

A concern I have is that it does not seem possible to render an empty array with ucfg, I did a few tests and the following manifest:

apiVersion: elasticsearch.k8s.elastic.co/v1
kind: Elasticsearch
metadata:
  name: quickstart
spec:
  version: 8.0.0
  image: docker.elastic.co/elasticsearch/elasticsearch:8.0.0-SNAPSHOT
  nodeSets:
    - name: coordinating
      podTemplate:
        spec:
          securityContext:
            runAsUser: 1000
            fsGroup: 1000
      count: 1
      config:
        node.roles: []
        node.store.allow_mmap: false
...

is rendered as:

node:
  roles: null
  store:
    allow_mmap: false

Which produces the following error:

Exception in thread "main" org.elasticsearch.ElasticsearchParseException: null-valued setting found for key [node.roles] found at line number [10], column number [10]

[pebrc]

I believe #3387 fixes this issue. Closing.