Setup a validator in the test genesis

[yihuang]

Extracted from: #1168

In cosmos-sdk 0.46's InitGenesis it reject Zero validators,
prepare for the upgrade of cosmos-sdk 0.46.

Description

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For contributor use:

• 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

---

For admin use:

• Added appropriate labels to PR (ex. WIP, R4R, docs, etc)
• Reviewers assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #1171 (e2bd6ff) into main (3d2f72a) will increase coverage by 0.52%.
The diff coverage is 90.78%.

@@            Coverage Diff             @@
##             main    #1171      +/-   ##
==========================================
+ Coverage   61.54%   62.06%   +0.52%     
==========================================
  Files          91       91              
  Lines        7281     7355      +74     
==========================================
+ Hits         4481     4565      +84     
+ Misses       2577     2562      -15     
- Partials      223      228       +5     

Impacted Files	Coverage Δ
app/utils.go	69.32% <90.78%> (+34.49%)	⬆️
app/app.go	86.00% <0.00%> (+0.44%)	⬆️

[fedekunze]

utACK