Add CUI base

[raa0121]

github.com/urfave/cli/v2 を使って、コマンドを作るところまで。
github.com/mattn/memo あたりが参考

[codecov]

Codecov Report

Merging #49 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #49   +/-   ##
=======================================
  Coverage   81.32%   81.32%           
=======================================
  Files          64       64           
  Lines        2362     2362           
=======================================
  Hits         1921     1921           
  Misses        324      324           
  Partials      117      117           

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