[curation] [multi-channel support] Only load selected channels during curation image loading

[yrkim98]

Currently we load entire multi channel images into curation even after selecting a channel. We need to only dispay the selected chanel in multi channel images in the viewer so that the segmentation correctly displays on top of the raw image.

[hughes036]

Useful experience in this wip : https://github.com/AllenCell/allencell-ml-segmenter/pull/244/files