[Snapshot + Restore] Add support for "feature states" on restore

[alisonelizabeth]

As of 7.12, a new field called feature_states can be included when restoring snapshots. We need to add support for this in the “Restore snapshot” form in the Snapshot and Restore UI.

Related to elastic/elasticsearch#63513.

ES behavior
By enabling include_global_state on restoration, system indices will be restored (if included in the snapshot). This behavior can be overridden to an extent by including the feature_states field, which contains an array of strings indicating the "feature" for which system indices should be snapshotted or restored. 

Example API request:

POST /_snapshot/my_repository/snapshot_2/_restore
{
  "indices": "index_1",
  "include_global_state": true,
  "feature_states": ["watcher", "security"]
}

UX proposal

• A combo box should display on the "Logistics" step of the “Restore snapshot” form with a list of available features to select. The features can be retrieved via a new api:

  GET /_snapshottable_features
  

• The combo box should only display if include_global_state is enabled.

• The logic added via [Snapshot + Restore] Add callout when restoring snapshot #95104 will need to be updated to account for feature states. See rules defined in Add a note in the UI when restoring a snapshot with include_global_state: true that system indices will be overwritten #92916 (comment).

• The "Review" step of the form should be updated to include any features selected by the users.

• The "Data streams and indices" section on the "Review" step should be updated to include the indices/data streams the user selected, in addition to any system indices that may be restored based on the features defined in feature_states. Note that this logic would only be applicable on 7.x. See Add a note in the UI when restoring a snapshot with include_global_state: true that system indices will be overwritten #92916 (comment) for more details.

[elasticmachine]

Pinging @elastic/es-ui (Team:Elasticsearch UI)

[sabarasaba]

Fixed with #131310