Checking for target_estimated and image timestamps alignment

compares the target_timestamp and the image_timestamp

Change-Id: Ifefcb00202fb13f8157b9b2506a940a165fbad69
Signed-off-by: Henry Speiser <henry@speiser.net>
diff --git a/y2022/vision/target_estimate.fbs b/y2022/vision/target_estimate.fbs
index 2621634..7dbc69f 100644
--- a/y2022/vision/target_estimate.fbs
+++ b/y2022/vision/target_estimate.fbs
@@ -41,8 +41,14 @@
 
   blob_result:BlobResultFbs (id: 2);
 
+  // Contains the duration between the epoch and the nearest point
+  // in time from when it was called.
+  image_monotonic_timestamp_ns:int64 (id: 3);
+
   // Information about the camera which took this image.
-  camera_calibration:frc971.vision.calibration.CameraCalibration (id: 3);
+  camera_calibration:frc971.vision.calibration.CameraCalibration (id: 4);
+
+  // TODO(milind): add confidence
 }
 
 root_type TargetEstimate;