Support worker threads with custom current working directory

[Lakitna]

Closes #130

[Lakitna]

So yeah that was to be expected. CI fails on Node < 12 due to worker threads not existing in those versions.

Cannot find module 'worker_threads'

[codecov]

Codecov Report

Merging #131 into master will not change coverage by %.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #131   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            7         7           
  Lines          162       165    +3     
  Branches        34        34           
=========================================
+ Hits           162       165    +3     

Impacted Files	Coverage Δ
lib/util/resolveCommand.js	100.00% <100.00%> (ø)

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[satazor]

See #132