Towards stateful router

[PumpkinSeed]

Closes: #5455

Description

Details in #5458

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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

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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 #5460 into ctx_msg_router will increase coverage by 0.01%.
The diff coverage is n/a.

@@                Coverage Diff                 @@
##           ctx_msg_router    #5460      +/-   ##
==================================================
+ Coverage           54.37%   54.39%   +0.01%     
==================================================
  Files                 313      313              
  Lines               18840    18840              
==================================================
+ Hits                10245    10248       +3     
+ Misses               7810     7807       -3     
  Partials              785      785

Impacted Files	Coverage Δ
x/mock/app.go	64.18% <0%> (+1.35%)	⬆️
baseapp/options.go	73.13% <0%> (+1.49%)	⬆️