Provide a parameter to disable rmarkdown report creation in the differential abundance pipeline

[shreya-sharma20]

Description of feature

When analyzing a large number of samples using the differential abundance pipeline, the markdown notebook compilation step fails due to memory issues.

• Error message: "Error: pandoc document conversion failed with error 9"
• Process causing this error: NFCORE_DIFFERENTIALABUNDANCE:DIFFERENTIALABUNDANCE:RMARKDOWNNOTEBOOK

For now, I have increased the memory for this process.

Feature Request: It'll be helpful if there is a parameter to disable this process if reports are not required.

[dshechter]

Additional suggestion to increase the RAM allocated for this process, e.g.

process {
    withName: 'NFCORE_DIFFERENTIALABUNDANCE:DIFFERENTIALABUNDANCE:RMARKDOWNNOTEBOOK' {
        memory = 200.GB
    }
}

Could work with less than 200, just haven't tried it.