Create Account on SendCoins

[alexanderbez]

With the merging of #5572, a regression occurred where when you send tokens to a new (non-existent account), the new account balance is created (in x/bank), but the actual account is not created in x/auth.

---

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 #5615 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #5615      +/-   ##
==========================================
- Coverage   53.42%   53.42%   -0.01%     
==========================================
  Files         322      322              
  Lines       19745    19748       +3     
==========================================
+ Hits        10549    10550       +1     
- Misses       8379     8381       +2     
  Partials      817      817

Impacted Files	Coverage Δ
x/bank/internal/keeper/keeper.go	84.73% <100%> (+0.18%)	⬆️
x/mock/app.go	65.24% <0%> (-1.22%)	⬇️

[tac0turtle]

is there an issue for this?

[alexanderbez]

@sunnya97 said he'd create an ADR for his "its on me" message idea.