Support multichannel images in pipeline

[KoenDesplenter]

Make sure that the pipeline supports multichannel images like the plant data. This support is needed for the cleaning and segmentation step

[ArneDefauw]

should be fixed by https://github.com/saeyslab/napari-sparrow/commit/147a627c56d0406281b600924181318a51168a1d . We both support:

• single .tiff files with multiple channels (e.g. plant resolve).
• multiple .tiff files with each tiff representing one separate channel, e.g. DAPI and PolyT (vizgen)

z-stack projection will also be done on each of these channels individually if more than one z-stack is available.

One spatialdata object will be created from either a single .tiff file, or multiple .tiff files.

Cleaning step will clean these channels individually. Segmentation step can use these multiple channels (i.e. one for cell boundary, one for nuclei).

Plotting functions (plot_shapes, segmentationPlot) now also take care of these channels.