Better handling of pcgr/pcgrr conda env custom naming

[pdiakumis]

Adding better support for custom naming of pcgr/pcgrr conda envs.

In short, we use the $CONDA_PREFIX variable to point us to the name of the main 'pcgr' conda env that is used to run the analysis.

With the --pcgrr_conda option (default: pcgrr), you're being explicit that the 'pcgrr' conda env will have a non-default name (e.g. baz_pcgrr).

$ echo $CONDA_PREFIX
/path/to/conda/foo_pcgr

Based on the above path, the main 'pcgr' conda env is called foo_pcgr. And there should be a baz_pcgrr directory sitting at the same level as foo_pcgr. These names/paths are important since they're used to call Rscript from the pcgrr conda env and to point to perl and loftee binaries/directories.

[sigven]

Works like a charm from my testing:)