Show node roles in Stack Monitoring ES instance listing

[smith]

Users of the instance listing would like to see what roles each Elasticsearch node is assigned.

Add a column called Roles between Status and Shards on the Elasticsearch nodes listing with a comma-separated list of the node roles for the instance.

[elasticmachine]

Pinging @elastic/infra-monitoring-ui (Team:Infra Monitoring UI)

[smith]

Looking in .monitoring-es-8 on a cluster and I see that there's an elasticsearch.node.roles field but no values present in the data I'm looking at.

The role also doesn't appear in data returned from the /api/monitoring/v1/clusters/:cluster_id/elasticsearch/nodes endpoint, just the "type". The type doesn't include the hot/warm status of a node, which is what we're after here, so we might have to gauge the difficulty of collecting and displaying this data.

[miltonhultgren]

When the recent Ingest Pipelines metricset was added, Josh introduced the new mapping for elasticsearch.node.roles but currently that metricset is the only one that populates that data (and you need to enable it).

So we'll need to update some metricset to collect that data, my guess is that the table is populated mostly by node_stats which pulls data from ES /_nodes/_all/stats which does have the roles for each node.