[SECENG-685] Add human-friendly outputs for policy commands

[sagar-connect]

Checklist

=========

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have checked for similar issues and haven't found anything relevant.
• This is not a security issue (which should be reported here: https://circleci.com/security/)
• I have read Contribution Guidelines.

Changes

=======

• Additionally print user-friendly command outputs for create, update and delete policy subcommands to stderr.
• Update test(s)

Rationale

=========
The current output format was focused towards scripting, but we also need human-friendly output for policy commands.

Considerations

==============

The human friendly output is logged to stderr, and machine parsable output (JSON) is output to the stdout right after.
This way we get both the info we need, without the need to having to choose between one, and also eliminating the need for special flags.

[codecov]

Codecov Report

Merging #759 (70e64bc) into master (571ae88) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #759      +/-   ##
==========================================
+ Coverage   32.60%   32.63%   +0.02%     
==========================================
  Files          46       46              
  Lines        5410     5412       +2     
==========================================
+ Hits         1764     1766       +2     
  Misses       3390     3390              
  Partials      256      256              

Impacted Files	Coverage Δ
cmd/policy/policy.go	81.73% <100.00%> (+0.16%)	⬆️

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