Added ci property to understand if a command is run by CI

[mfbz]

Closes #1926

Description

Added "ci" property to data sent to mixpanel while running a command, to understand if the command is run by a ci provider or not.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 28.26%. Comparing base (a916fd7) to head (4e04573).

Files with missing lines	Patch %	Lines
internal/command/command.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1927      +/-   ##
==========================================
- Coverage   28.26%   28.26%   -0.01%     
==========================================
  Files          95       95              
  Lines        6591     6592       +1     
==========================================
  Hits         1863     1863              
- Misses       4546     4547       +1     
  Partials      182      182              

Flag	Coverage Δ
unittests	28.26% <0.00%> (-0.01%)	⬇️

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