R4R: Add indent to JSON of gaiacli key [add|show|list]

[yangyanqing]

• Targeted PR against correct branch (see CONTRIBUTING.md)

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.(Just print format)

• Wrote tests (Just print format, but I had tested)

• Updated relevant documentation (docs/)

• Added entries in PENDING.md with issue #

• rereviewed Files changed in the github PR explorer

---

For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #3841 into develop will decrease coverage by <.01%.
The diff coverage is 60%.

@@             Coverage Diff             @@
##           develop    #3841      +/-   ##
===========================================
- Coverage    60.92%   60.92%   -0.01%     
===========================================
  Files          192      192              
  Lines        14323    14331       +8     
===========================================
+ Hits          8727     8731       +4     
- Misses        5027     5031       +4     
  Partials       569      569

[codecov]

Codecov Report

Merging #3841 into develop will decrease coverage by 0.01%.
The diff coverage is 64.7%.

@@             Coverage Diff             @@
##           develop    #3841      +/-   ##
===========================================
- Coverage    60.94%   60.92%   -0.02%     
===========================================
  Files          192      192              
  Lines        14346    14337       -9     
===========================================
- Hits          8743     8735       -8     
+ Misses        5033     5029       -4     
- Partials       570      573       +3

[jackzampolin]

Can this PR make the usage of --indent consistent across the keys package. I've noted the two other commands that need to be similarly amended.

Also there needs to be an entry in PENDING.md for this change as well. Thank you for your contribution!

[alexanderbez]

LGTM. Lets get this merged @jackzampolin