add 'Label' inference to reading with ndev-reader

[TimMonko]

Most likely, infer from something opinionated like 'labels', 'masks', etc., in metadata (likely BioImage.channel_names) that something is a labels layer, and instead add as a layer label. Also, add a default opacity (likely 70%, to match napari default) to these added labels.

Consider also that something like a uint image with a max of 1 represents a binary image, and read as a labels. Not sure if a data-approach can be used for others, since both labels and images share the same dtypes frequently -- maybe u/int32/64 are safe?