Missing TopMetrics aggregation

Similar to https://github.com/elastic/elasticsearch-dsl-py/issues/1628 and https://github.com/elastic/elasticsearch-dsl-py/issues/1630, the [top_metrics aggregation](https://www.elastic.co/guide/en/elasticsearch/reference/8.12/search-aggregations-metrics-top-metrics.html) is missing from `aggs.py`.