g2gtools: add vci_build process

src/nf_modules/g2gtools/main.nf

+version = "0.2.8"
+container_url = "lbmc/g2gtools:${version}"
+
+process vci_build {
+  container = "${container_url}"
+  label "big_mem_multi_cpus"
+  tag "$file_id"
+
+  input:
+    tuple val(file_id), path(vcf)
+    tuple val(ref_id), path(fasta), path(fai), path(dict)
+  output:
+    tuple val(file_id), path("*.chain"), emit: vci
+  script:
+"""
+g2gtools vcf2vci \
+  -p ${task.cpus} \
+  -f ${fasta} \
+  -i ${vcf} \
+  -s ${file_id} \
+  -o ${file_id}.vci
+"""
+}
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