Add option to ignore selector warnings to pipeline template

[drpatelh]

Inspired by nextflow-io/nextflow#2700 (comment)

This will mean that process selector warnings are not shown by default when running pipelines. However, if -profile devel is used then they are shown to find and fix any configuration issues. Could go for other names too e.g. dev (clashes with branch names?), development etc. or we can include it as part of the existing debug profile.

Will need to update the developer docs on the website and contributing docs / issue and PR templates in the pipeline template to suggest using this profile when writing pipelines.

[matthdsm]

I think it would make the most sense to add this to the debug profile. That way we avoid any possible name collision

[fa2k]

The default has now been changed to hide the process selector warnings, with a possibility to re-enable them with the debug profile. This will be less confusing for end users. Thanks for the issue drpatelh.