Datasource/CloudWatch: Better handling of stats grouping (#24789)

* Datasource/CloudWatch: Better handling of stats grouping

pkg/tsdb/cloudwatch/sort_frame.go

@@ -0,0 +1,41 @@
+package cloudwatch
+
+import (
+	"time"
+
+	"github.com/grafana/grafana-plugin-sdk-go/data"
+)
+
+// ByTime implements sort.Interface for data.Frame based on the frame's time field
+type ByTime data.Frame
+
+func (a ByTime) Len() int {
+	if len(a.Fields) > 0 {
+		return a.Fields[0].Len()
+	}
+
+	return 0
+}
+
+func (a ByTime) Swap(i, j int) {
+	for _, field := range a.Fields {
+		temp := field.At(i)
+		field.Set(i, field.At(j))
+		field.Set(j, temp)
+	}
+}
+func (a ByTime) Less(i, j int) bool {
+	var timeField *data.Field = nil
+	for _, field := range a.Fields {
+		if field.Type() == data.FieldTypeNullableTime {
+			timeField = field
+			break
+		}
+	}
+
+	if timeField == nil {
+		return false
+	}
+
+	return (timeField.At(i).(*time.Time)).Before(*timeField.At(j).(*time.Time))
+}