build: replace npm scripts to cmdx

[suzuki-shunsuke]

https://github.com/suzuki-shunsuke/cmdx

[codecov-io]

Codecov Report

Merging #31 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #31   +/-   ##
=======================================
  Coverage   85.13%   85.13%           
=======================================
  Files           4        4           
  Lines         296      296           
=======================================
  Hits          252      252           
  Misses         32       32           
  Partials       12       12

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b476095...bc5db2a. Read the comment docs.