nf_modules: add bedtools for DSL2

src/nf_modules/bedtools/main.nf

+version = "2.25.0"
+container_url = "lbmc/bedtools:${version}"
+
+process fasta_from_bed {
+  container = "${container_url}"
+  label "big_mem_mono_cpus"
+  tag "${bed.baseName}"
+  publishDir "results/fasta/", mode: 'copy'
+
+  input:
+  path fasta
+  path bed
+
+  output:
+  path "*_extracted.fasta", emit: fasta
+
+  script:
+"""
+bedtools getfasta -name \
+-fi ${fasta} -bed ${bed} -fo ${bed.baseName}_extracted.fasta
+"""
+}