feat: add disparity messages

events/events.proto

@@ -15,6 +15,14 @@ message FrameMessage {
     bytes frame = 2;
 }
 
+message DisparityMessage {
+    FrameRef frame_ref= 1;
+    bytes disparity = 2;
+    double focal_length_in_pixels = 3;
+    // the distance between two mono cameras
+    double baseline_in_mm = 4;
+}
+
 message SteeringMessage {
     float steering = 1;
     float confidence = 2;