Handle empty files

[k1sauce]

This PR fixes #5612
This PR also handles empty FASTQ files by including a empty fastq emit channel

[glichtenstein]

Needs a way to avoid sending falco empty fastqs. Modifying falco module itself looked straighforward to me but it seems I was not aware that it will cause other troubles as stated by the reviewer: #5769 (review), I will close my PR then.

[SPPearce]

Why is the read group parsing being removed?

[k1sauce]

This is a mistake on my part. I thought the read group parsing would download a local copy of the FASTQ file when the file was in cloud storage. Thus, I decided to remove it. However, I see now that it is a buffered Input stream and the file is not downloaded. I will add the read group parsing back in.

[k1sauce]

This should be ready to go now. I had trouble with the nf-test for BCL Convert. The problem was that the test data file permissions were too restrictive. Because the GitHub action is self hosted with rootless docker, the test is executed as the host user and it could not read the test data when the volume is mounted. The fix was to change the test data file permissions to 775. It was an easy fix but it took me awhile to figure out what was going wrong. I found this explanation helpful https://joeeey.com/blog/rootless-docker-avoiding-common-caveats/#storage-fixes.

[SPPearce]

@matthdsm , @glichtenstein, are you happy with this?

[matthdsm]

👍🏻