fix: fix the path error on windows

[w1zd]

1. windows doesnt have /dev/null, use NUL instead.
2. root dir in windows looks like D: C:, add related logic to function resolveConfig

#44

[codecov]

Codecov Report

Merging #60 (b55b4d9) into master (b2ef85c) will decrease coverage by 0.34%.
The diff coverage is 80.00%.

@@            Coverage Diff             @@
##           master      #60      +/-   ##
==========================================
- Coverage   98.86%   98.51%   -0.35%     
==========================================
  Files          13       13              
  Lines         351      405      +54     
  Branches        0       57      +57     
==========================================
+ Hits          347      399      +52     
- Misses          4        6       +2     

Impacted Files	Coverage Δ
lib/base_command.js	98.49% <80.00%> (-0.62%)	⬇️
lib/cache.js	97.72% <0.00%> (-2.28%)	⬇️
lib/program.js	100.00% <0.00%> (ø)
lib/command/run.js	100.00% <0.00%> (ø)
lib/command/find.js	100.00% <0.00%> (ø)
lib/command/init.js	100.00% <0.00%> (ø)
lib/command/sync.js	100.00% <0.00%> (ø)
lib/command/remove.js	100.00% <0.00%> (ø)
lib/command/runall.js	100.00% <0.00%> (ø)
... and 2 more

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