parameterize container registry

[junjun-zhang]

Parameterizing container registry will allow us to customize container registry at pipeline execution time instead of hardcoding it at development time.

This will need to be implemented at each process/module level.

[junjun-zhang]

This can now to supported at individual tool/process level, eg, https://github.com/icgc-argo/dna-seq-processing-wfs/blob/main/wfpr_modules/github.com/icgc-argo/data-processing-utility-tools/payload-gen-seq-experiment%400.4.0/main.nf#L27-L40