R4R: gaiakeyutil -> gaiacli keys parse

[alessio]

Incorporate gaiakeyutil functionalities into gaiacli.

We would neither build nor install gaiakeyutil anymore, key string simple parsing functionality would be merged into gaiacli keys parse.

This is a call for a preliminary review, pending entry will eventually be added.

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.
• Wrote tests
• Updated relevant documentation (docs/)
• Added a relevant changelog entry: sdkch add [section] [stanza] [message]
• 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 #4228 into master will increase coverage by 0.07%.
The diff coverage is 75.8%.

@@            Coverage Diff             @@
##           master    #4228      +/-   ##
==========================================
+ Coverage   60.16%   60.24%   +0.07%     
==========================================
  Files         212      213       +1     
  Lines       15188    15250      +62     
==========================================
+ Hits         9138     9187      +49     
- Misses       5421     5432      +11     
- Partials      629      631       +2

[fedekunze]

LGTM, although do we want to add a test case for the CLI and update the docs too ?

[alessio]

@fedekunze this small utility hadn't made it into docs back then - I'm planning to incorporate gaiareplay into gaiacli as well, which too is undocumented. I'll add all relevant docs in an ensuing PR if you don't mind @fedekunze

[alexanderbez]

TestedACK.

[alexanderbez]

testedACK.