Add functions for sending slack notifications from nextflow
Add functions for sending slack notifications from nextflow

Three ways - using processes in a pipeline, either a simple message or a 
whole file. This uses the rnac utility, so this function is also 
available anywhere that utility is used.

The other way uses groovy's built in request functionality. This one is 
a bit simpler for now, but allows us to send messages from closures 
(e.g. onComplete and onError)

RNAcentral/rnacentral-import-pipeline,RNAcentral/rnacentral-import-pipeline,RNAcentral/rnacentral-import-pipeline,RNAcentral/rnacentral-import-pipeline