Support of minimap2, bam mem2 and bwa aln

[agalitsyna]

Adding an opportunity to select the aligner out of:

• minimap2 and single-end data distiller with an option to process with minimap2  #177
  • requires mapping with parse2 instead of parse
• bwa mem2 which is a fast optimized bwa mem
• bwa aln optimized for single end https://github.com/open2c/distiller-nf/pull/171/files

Pros:

• flexibility for multiple types of data
  Cons:
• reduced readability
• more code and params

[mxw010]

if you were to add those mapper, would you consider adding chromap as well? In our experience it performs just as well and is significantly faster.