### Description

Elasticsearch defines the concept of a [feature](https://www.elastic.co/guide/en/elasticsearch/reference/current/get-features-api.html) for the purpose of better managing them when snapshotting/restoring them via the [feature_states field](https://www.elastic.co/guide/en/elasticsearch/reference/current/create-snapshot-api.html#create-snapshot-api-feature-states)

The `shards_availability` health indicator currently diagnoses the condition of indices needing to be [restored from a snapshot](https://github.com/elastic/elasticsearch/blob/main/server/src/main/java/org/elasticsearch/cluster/routing/allocation/ShardsAvailabilityHealthIndicatorService.java#L138) and recommends a [troubleshooting guide](http://ela.st/restore-snapshot)

However, since `8.x` the restore API **must** use `feature_states` instead of specifying systems indices or system data streams as part of the `indices` field.

This proposes the `affected_resources` for the `restore_from_snapshot` diagnosis return the indices that are not part of a `feature` under the `INDICES` type, and a new type `FEATURES`.
e.g. instead of current behaviour
```
"affected_resources": {
  "indices": [
    ".geoip_databases",
    "test_index"
    ]
}
```
we could return:
```
"affected_resources": {
  "indices": [
    "test_index"
   ], 
  "features": [
     "geoip"
  ]
}
```



server/src/main/java/org/elasticsearch/node/Node.java
import org.elasticsearch.bootstrap.BootstrapCheck;
import org.elasticsearch.bootstrap.BootstrapContext;
import org.elasticsearch.client.internal.Client;
import org.elasticsearch.client.internal.node.NodeClient;
import org.elasticsearch.cluster.ClusterInfoService;
import org.elasticsearch.cluster.ClusterModule;
import org.elasticsearch.cluster.ClusterName;
import org.elasticsearch.cluster.ClusterState;
import org.elasticsearch.cluster.ClusterStateObserver;
import org.elasticsearch.cluster.InternalClusterInfoService;
import org.elasticsearch.cluster.NodeConnectionsService;
import org.elasticsearch.cluster.action.index.MappingUpdatedAction;
import org.elasticsearch.cluster.coordination.CoordinationDiagnosticsService;
import org.elasticsearch.cluster.coordination.Coordinator;
import org.elasticsearch.cluster.coordination.MasterHistoryService;
import org.elasticsearch.cluster.coordination.StableMasterHealthIndicatorService;
import org.elasticsearch.cluster.desirednodes.DesiredNodesSettingsValidator;
import org.elasticsearch.cluster.metadata.IndexMetadataVerifier;
import org.elasticsearch.cluster.metadata.IndexTemplateMetadata;
import org.elasticsearch.cluster.metadata.Metadata;
import org.elasticsearch.cluster.metadata.MetadataCreateDataStreamService;
import org.elasticsearch.cluster.metadata.MetadataCreateIndexService;
import org.elasticsearch.cluster.metadata.MetadataDataStreamsService;
import org.elasticsearch.cluster.metadata.MetadataIndexTemplateService;
import org.elasticsearch.cluster.metadata.MetadataUpdateSettingsService;
import org.elasticsearch.cluster.metadata.SystemIndexMetadataUpgradeService;
import org.elasticsearch.cluster.metadata.TemplateUpgradeService;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.cluster.node.DiscoveryNodeRole;
import org.elasticsearch.cluster.routing.BatchedRerouteService;