Migrate Search Detector tasks to SDK using SDKRestClient

[dbwiddis]

Is your feature request related to a problem?

Part of opensearch-project/OpenSearch#5224

What solution would you like?

Migrate the Search Detector tasks Rest API to Extensions SDK using SDKRestClient.

Use the implementation of #353 as a reference. Add new issues for any steps you skip.

Implement the following API endpoints:

• GET _plugins/_anomaly_detection/detectors/tasks/_search
• POST _plugins/_anomaly_detection/detectors/tasks/_search

[owaiskazi19]

The migration work is done in the attached PR.
Wasn't able to test the workflow as the API fails with

 "error": "Request failed with exception: [[.opendistro-anomaly-detection-state] OpenSearchStatusException[OpenSearch exception [type=index_not_found_exception, reason=no such index [.opendistro-anomaly-detection-state]]]]"

.opendistro-anomaly-detection-state index will be created as the part of #383

[owaiskazi19]

API: 127.0.0.1:9200/_extensions/_ad-extension/detectors/tasks/_search with GET and POST
Query:

{
  "query": {
    "bool": {
      "filter": [
        {
          "term": {
            "detector_id": "-TZfXYcBZWahDDF-C6Mh"
          }
        },
        {
          "term": {
            "task_type": "REALTIME_SINGLE_ENTITY"
          }
        },
        {
          "term": {
            "is_latest": "true"
          }
        }
      ]
    }
  }
}

Response:

{
    "took": 15,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 1,
            "relation": "eq"
        },
        "max_score": 0.0,
        "hits": [
            {
                "_index": ".opendistro-anomaly-detection-state",
                "_id": "-zZfXYcBZWahDDF-a6MO",
                "_version": 1,
                "_seq_no": 105,
                "_primary_term": 29,
                "_score": 0.0,
                "_source": {
                    "detector_id": "-TZfXYcBZWahDDF-C6Mh",
                    "task_progress": 0.0,
                    "last_update_time": 1680898747146,
                    "execution_start_time": 1680898747146,
                    "state": "CREATED",
                    "task_type": "REALTIME_SINGLE_ENTITY",
                    "init_progress": 0.0,
                    "is_latest": true,
                    "detector": {
                        "description": "Test detector",
                        "feature_attributes": [
                            {
                                "feature_id": "n4JeXYcBnxLZhpku4uYI",
                                "feature_enabled": true,
                                "feature_name": "test",
                                "aggregation_query": {
                                    "test": {
                                        "sum": {
                                            "field": "value"
                                        }
                                    }
                                }
                            }
                        ],
                        "schema_version": 0,
                        "time_field": "timestamp",
                        "last_update_time": 1680898722589,
                        "indices": [
                            "server_log*"
                        ],
                        "window_delay": {
                            "period": {
                                "unit": "Minutes",
                                "interval": 1
                            }
                        },
                        "result_index": "opensearch-ad-plugin-result-test1",
                        "detection_interval": {
                            "period": {
                                "unit": "Minutes",
                                "interval": 1
                            }
                        },
                        "name": "test-detector13",
                        "filter_query": {
                            "bool": {
                                "filter": [
                                    {
                                        "range": {
                                            "value": {
                                                "include_lower": false,
                                                "include_upper": true,
                                                "from": 1,
                                                "boost": 1.0,
                                                "to": null
                                            }
                                        }
                                    }
                                ],
                                "adjust_pure_negative": true,
                                "boost": 1.0
                            }
                        },
                        "shingle_size": 8,
                        "detector_type": "SINGLE_ENTITY"
                    }
                }
            }
        ]
    }
}