sdata does not save when chunks are not equal

[lotte-vandevreken]

When trying to save the sdata to .zarr, it gives an error when the chunks are not equal (for example after cropping the sdata with the bounding_box_query function). The error was fixed after running sdata[image].data = sdata[image].data.rechunk() and sdata[label].data = sdata[label].data.rechunk() for all images and labels.

Maybe this could be added as an extra option to the sdata.write function?

cc. @giovp @lopollar