[Feature]: Align plugin configuration syntax with standard Nextflow style

[nadnein]

Description:

Our plugin configuration should match the style and conventions used in native Nextflow configuration blocks. This improves readability, consistency, and makes the setup directly usable with remote storage such as S3 buckets.

Proposed change (proposed in #309):

// In nextflow.config
plugins {
    id 'nf-co2footprint@1.0.0'
}

params {
    outdir = "s3://my-bucket/pipeline-results"
}

co2summary {
    enabled = true
    file    = "${params.outdir}/pipeline_info/co2footprint_summary_${trace_timestamp}.txt"
}
co2trace {
    enabled = true
    file    = "${params.outdir}/pipeline_info/co2footprint_trace_${trace_timestamp}.txt"
}
co2report {
    enabled = true
    file    = "${params.outdir}/pipeline_info/co2footprint_report_${trace_timestamp}.html"
}

[mwhamgenomics]

Linking @JosuaCarl's comment from #309, sugesting an alternate format with a single top-level:

co2footprint {
    trace {
        enabled = true
        file = /path/to/file
    }
}