Update MACSima reader when stitching is supported

[melonora]

Talking with @m-albert at the ome-ngff hackathon, he has support for stitching using SpatialImage. We agreed to work together on adding the API for this in SpatialData. Once this work has been completed the MACSima reader as added with #224 should be revisited. This would also allow pipelines such as MCMICRO to use SpatialData throughout the pipeline. cc @kbestak

[m-albert]

Here's some example code for obtaining a stitched SpatialImage using multiview-stitcher.

Just leaving a message here that I'm afk for the next two weeks and looking forward to discuss and work on a stitching API together after that @melonora.