LastImportTime for resource. (#112153)

* LastImportTime for resource.

* Make StorageBackendImpl implement GetResourceLastImportTimes

* More missing implementations of GetResourceLastImportTimes

* Fix import.

* Skip TestGetResourceLastImportTime in TestBadgerKVStorageBackend.

* Implement GetResourceLastImportTimes by mockStorageBackend

* Bump test tolerance.

* Fix postgres query and timezone.

* Fix postgres query and timezone.

* Make linter happy.

pkg/storage/unified/sql/backend.go

@@ -955,3 +955,51 @@ func (b *backend) fetchLatestHistoryRV(ctx context.Context, x db.ContextExecer,
 	}
 	return res.ResourceVersion, nil
 }
+
+func (b *backend) GetResourceLastImportTimes(ctx context.Context) iter.Seq2[resource.ResourceLastImportTime, error] {
+	ctx, span := b.tracer.Start(ctx, tracePrefix+"GetLastImportTimes")
+	defer span.End()
+
+	rows, err := dbutil.QueryRows(ctx, b.db, sqlResourceLastImportTimeQuery, &sqlResourceLastImportTimeQueryRequest{SQLTemplate: sqltemplate.New(b.dialect)})
+	if err != nil {
+		return func(yield func(resource.ResourceLastImportTime, error) bool) {
+			yield(resource.ResourceLastImportTime{}, err)
+		}
+	}
+
+	return func(yield func(resource.ResourceLastImportTime, error) bool) {
+		closeOnDefer := true
+		defer func() {
+			if closeOnDefer {
+				_ = rows.Close() // Close while ignoring errors.
+			}
+		}()
+
+		for rows.Next() {
+			// If context has finished, return early.
+			if ctx.Err() != nil {
+				yield(resource.ResourceLastImportTime{}, ctx.Err())
+				return
+			}
+
+			row := resource.ResourceLastImportTime{}
+			err = rows.Scan(&row.Namespace, &row.Group, &row.Resource, &row.LastImportTime)
+			if err != nil {
+				yield(resource.ResourceLastImportTime{}, err)
+				return
+			}
+
+			if !yield(row, nil) {
+				return
+			}
+		}
+
+		closeOnDefer = false
+
+		// Close and report error, if any.
+		err := rows.Close()
+		if err != nil {
+			yield(resource.ResourceLastImportTime{}, err)
+		}
+	}
+}