add regression report generator (#7094)

Stack from [ghstack](https://github.com/ezyang/ghstack) (oldest at
bottom):
* #7112
* #7096
* #7095
* __->__ #7094

main class to detect regression
1. use baseline data to generate baseline for regression detection,
currently support (max,min, latest, earliest) within the baseline data
window
2. decide wether the target data list under the threshold for regression
detection based on the baseline value.
3. if detected more than 2 continuous dp from current timestamp, mark as
regression

Author: yangw-dev

aws/lambda/benchmark_regression_summary_report/common/benchmark_time_series_api_model.py

@@ -1,5 +1,6 @@
+import datetime as dt
 from dataclasses import dataclass, field
-from typing import Any, Dict, List
+from typing import Any, Dict, List, Optional
 
 import requests
 
@@ -62,3 +63,24 @@ def from_request(
         except Exception as e:
             raise RuntimeError(f"Malformed API payload: {e}")
         return cls(data=BenchmarkTimeSeriesApiData(time_series=ts, time_range=tr))
+
+
+def get_latest_meta_info(
+    time_series: List[BenchmarkTimeSeriesItem],
+) -> Optional[dict[str, Any]]:
+    if not time_series:
+        return None
+
+    pts = [p for s in time_series for p in s.data]
+    latest = max(
+        pts,
+        key=lambda p: dt.datetime.fromisoformat(
+            p["granularity_bucket"].replace("Z", "+00:00")
+        ),
+    )
+    return {
+        "commit": latest.get("commit", ""),
+        "branch": latest.get("branch", ""),
+        "timestamp": latest.get("granularity_bucket", ""),
+        "workflow_id": latest.get("workflow_id", ""),
+    }