the ability to specify --unknown-slide

[aguang]

Description of feature

It doesn't seem like with the nextflow pipeline that there is a way to specify --unknown-slide (as described here: https://www.10xgenomics.com/support/software/space-ranger/latest/analysis/inputs/image-slide-parameters) as an option instead of --slide and --area. If there is a way to do so, could you point me to it? And if not, can this be implemented as a feature given that it's a space ranger option?