Isolate R to look for packages in container only

[drpatelh]

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• Fixes Isolate R library paths to those in container #541
• Tested by @mashehu on the atacseq pipeline DESeq2 dependency incompatibility atacseq#94

[codecov]

Codecov Report

Merging #586 into dev will not change coverage by %.
The diff coverage is n/a.

@@           Coverage Diff           @@
##              dev     #586   +/-   ##
=======================================
  Coverage   64.92%   64.92%           
=======================================
  Files          12       12           
  Lines        1796     1796           
=======================================
  Hits         1166     1166           
  Misses        630      630           

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