x/params: CLI Refactor & In-Process Tests

[alexanderbez]

Description

ref: #6423

---

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

• 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.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer
• Review Codecov Report in the comment section below once CI passes

[codecov]

Codecov Report

Merging #6720 into master will increase coverage by 0.04%.
The diff coverage is 36.36%.

@@            Coverage Diff             @@
##           master    #6720      +/-   ##
==========================================
+ Coverage   59.19%   59.23%   +0.04%     
==========================================
  Files         512      512              
  Lines       31295    31299       +4     
==========================================
+ Hits        18525    18541      +16     
+ Misses      11363    11347      -16     
- Partials     1407     1411       +4