Submit subworkflows to nf-core/modules and (re-) import them here

[matthdsm]

Description of feature

Future plans for demultiplex workflow:

Attempt to convert into atomic subworkflows:

1. wrap different demux strategies into subworkflows:

• demultiplex_illumina (bcl-convert, bcl2fastq)
• demultiplex_element (bases2fastq)
• demultiplex_singlecell (cellranger, contributed by @apeltzer)

2. wrap subworkflows into self contained subworkflow and submit to modules
3. Wrap subworkflow into stand-alone demutliplex workflow with qc steps etc, baked in.

Open for comment!

cfr https://nfcore.slack.com/archives/CL88J906S/p1665042215379769

[edmundmiller]

nf-core/modules#2198

[grst]

By now all demultiplxing routes are separate (local) subworkflows, but they are not submitted to nf-core/modules yet.