stage files to tmp files, then atomically move

[jchorl]

Fixes #1552

The comments should explain it. I tested locally.

[pditommaso]

Thanks for this contribution! please have a look at my comment.

[jchorl]

PTAL @pditommaso

[pditommaso]

Thanks for contributing to the project!

[pditommaso]

and obviously the devil hides in the details! Fails using S3 :/

Aug-21 11:10:11.055 [Actor Thread 9] ERROR nextflow.processor.TaskProcessor - Error executing process > 'MULTIQC'

Caused by:
  java.lang.UnsupportedOperationException

java.lang.UnsupportedOperationException: null
	at com.upplication.s3fs.S3FileSystemProvider.move(S3FileSystemProvider.java:558)
	at nextflow.file.FileHelper.movePath(FileHelper.groovy:846)
	at nextflow.file.FilePorter$FileTransfer.stageForeignFile0(FilePorter.groovy:297)
	at nextflow.file.FilePorter$FileTransfer.stageForeignFile(FilePorter.groovy:258)
	at nextflow.file.FilePorter$FileTransfer.run(FilePorter.groovy:244)