Change the get data stream api to include the following properties of a data stream:

- ~~Add `index_mode` from `DataStream` to the response.~~
- For each backing index of a data stream with time series index mode, include the temporal range the backing index represents (based on the `index.time_series.start_time` and `index.time_series.end_time` index settings.
server/src/main/java/org/elasticsearch/action/datastreams/GetDataStreamAction.java
}
            @Nullable
            public String getIlmPolicy() {
                return ilmPolicyName;
            }
            @Override
            public void writeTo(StreamOutput out) throws IOException {
                dataStream.writeTo(out);
                dataStreamStatus.writeTo(out);
                out.writeOptionalString(indexTemplate);
                out.writeOptionalString(ilmPolicyName);
            }
            @Override
            public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
                builder.startObject();
                builder.field(DataStream.NAME_FIELD.getPreferredName(), dataStream.getName());
                builder.field(DataStream.TIMESTAMP_FIELD_FIELD.getPreferredName(), dataStream.getTimeStampField());
                builder.xContentList(DataStream.INDICES_FIELD.getPreferredName(), dataStream.getIndices());
                builder.field(DataStream.GENERATION_FIELD.getPreferredName(), dataStream.getGeneration());
                if (dataStream.getMetadata() != null) {
                    builder.field(DataStream.METADATA_FIELD.getPreferredName(), dataStream.getMetadata());
                }
                builder.field(STATUS_FIELD.getPreferredName(), dataStreamStatus);
                if (indexTemplate != null) {
                    builder.field(INDEX_TEMPLATE_FIELD.getPreferredName(), indexTemplate);
                }
                if (ilmPolicyName != null) {
                    builder.field(ILM_POLICY_FIELD.getPreferredName(), ilmPolicyName);
                }
                builder.field(HIDDEN_FIELD.getPreferredName(), dataStream.isHidden());