Extract cmd package

[Fs02]

• Extract cmd package to github.com/go-rel/cmd
• This should make breaking changes less prone to cyclic dependency introduced by cmd test

[codecov]

Codecov Report

Base: 100.00% // Head: 100.00% // No change to project coverage 👍

Coverage data is based on head (7acaa72) compared to base (726f0b3).
Patch has no changes to coverable lines.

Additional details and impacted files

@@            Coverage Diff             @@
##            master      #319    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files           35        33     -2     
  Lines         2884      2766   -118     
==========================================
- Hits          2884      2766   -118     

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.