Quiet failures should drop a message file

[keiranmraine]

For consumption by sgcrispr-interim.

Having a file dropped when QC fails with a message to display to users will allow sgcrispr-interim to display this with no code changes, only configuration. This would be the preferred method over plots just being absent or having to parse logs.

[keiranmraine]

Alternative option 1:

• Create a "failure" version of all files (where fail is acceptable)
• Have last step of nextflow get list of all absent files and put "failure" version in place (where appropriate)

Alternative option 2:

Create a file containing a listing of all "optional" results that are absent as a one stop place to look rather than searching logs.