Nice-to-have: Add ability to load and move hex centroids

[calderast]

It would be nice to be able to load an already-created hex centroids file and have them overlayed on a video frame of the maze of the current day to see if they are still good. Our maze doesn't move often so we don't really need to re-click centroids each day, but we definitely should confirm they are still accurate before proceeding. Maybe with a hex overlay also (instead of just the centroid dots) so we can see how everything fits together.

Even better - be able to move individual centroids so we can adjust some things without needing to re-click all of them. This would be a nice part of our process in general - make centroids, load them with a hex overlay, and then be able to move individual ones until it's just right

[calderast]

Also, apparently for some older sessions (IM-1594) DLC used a cropped version of the video. So add the ability to add an x shift and y shift to the centroids so they match this cropped video used for position assignment