Fix for #219 - Bad python2 file lost in the bin folder

[cimendes]

This PR fixes the issues raised in #219. I've moved the problematic file from the bin folder and into templates, updating it to python3. I've also adjusted the components "remove_host" and "retrieve_mapped" to handle this template file.

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This change is 

[codecov-io]

Codecov Report

Merging #224 into dev will decrease coverage by 1%. The diff coverage is 0%.

@@            Coverage Diff             @@
##              dev     #224      +/-   ##
==========================================
- Coverage   42.34%   41.34%   -1.01%     
==========================================
  Files          72       73       +1     
  Lines        6529     6584      +55     
==========================================
- Hits         2765     2722      -43     
- Misses       3764     3862      +98

Impacted Files	Coverage Δ
flowcraft/generator/components/metagenomics.py	100% <ø> (ø)	:arrow_up:
flowcraft/generator/components/mapping.py	100% <ø> (ø)	:arrow_up:
flowcraft/templates/renamePE_samtoolsFASTQ.py	0% <0%> (ø)

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