Replace subworkflow/helpers.nf print_parameters to programatically log params

[tonyliang19]

• Should use this sample code:

Channel.of(params)
    .map { log -> groovy.json.JsonOutput.prettyPrint(groovy.json.JsonOutput.toJson(log)) }
    .collectFile(name: "log_params.json")
    .set { ch_log_params }