### Description

Given we have registered remotes and are able to cross cluster search/replicate I would like to be able to reindex a remote index on the local cluster.

The normal index from remote requires a host to be set. The proxy endpoint used for the remote doesn't work as that's over transport and index from remote uses the http/REST interface. Using the ES rest requires a user to be created with the correct permission, effectively not using the registered remote.

Doing a local index results in index not found:

```
# normal search works
POST remote1:example-index/_search

# results in index not found
POST _reindex
{
  "source": {
    "index": "remote1:example-index"
  },
  "dest": {
    "index": "my-new-example-index"
  }
}
```

```
{
  "error" : {
    "root_cause" : [
      {
        "type" : "index_not_found_exception",
        "reason" : "no such index [remote1:example-index]",
        "resource.type" : "index_or_alias",
        "resource.id" : "remote1:example-index",
        "index_uuid" : "_na_",
        "index" : "remote1:example-index"
      }
    ],
    "type" : "index_not_found_exception",
    "reason" : "no such index [remote1:example-index]",
    "resource.type" : "index_or_alias",
    "resource.id" : "remote1:example-index",
    "index_uuid" : "_na_",
    "index" : "remote1:example-index"
  },
  "status" : 404
}
```

modules/reindex/src/main/java/org/elasticsearch/reindex/ReindexValidator.java
*/
    static CharacterRunAutomaton buildRemoteWhitelist(List<String> whitelist) {
        if (whitelist.isEmpty()) {
            return new CharacterRunAutomaton(Automata.makeEmpty());
        }
        Automaton automaton = Regex.simpleMatchToAutomaton(whitelist.toArray(Strings.EMPTY_ARRAY));
        automaton = MinimizationOperations.minimize(automaton, Operations.DEFAULT_DETERMINIZE_WORK_LIMIT);
        if (Operations.isTotal(automaton)) {
            throw new IllegalArgumentException(
                "Refusing to start because whitelist "
                    + whitelist
                    + " accepts all addresses. "
                    + "This would allow users to reindex-from-remote any URL they like effectively having Elasticsearch make HTTP GETs "
                    + "for them."
            );
        }
        return new CharacterRunAutomaton(automaton);
    }
    /**
     * Throws an ActionRequestValidationException if the request tries to index
     * back into the same index or into an index that points to two indexes.
     * This cannot be done during request validation because the cluster state
     * isn't available then. Package private for testing.
     */
    static void validateAgainstAliases(
        SearchRequest source,
        IndexRequest destination,
        RemoteInfo remoteInfo,
        IndexNameExpressionResolver indexNameExpressionResolver,
        AutoCreateIndex autoCreateIndex,