fix: correctly coalesce coins even with repeated denominations(backport cosmos/cosmos-sdk#13265) (backport #1313)

[mergify]

Description

• (audit issue) correctly coalesce coins even with repeated denominations
  • backport fix: types: correctly coalesce coins even with repeated denominations & simplify logic cosmos/cosmos-sdk#13265

Motivation and context

How has this been tested?

Screenshots (if appropriate):

Checklist:

• I followed the contributing guidelines and code of conduct.
• I have added a relevant changelog to CHANGELOG.md
• I have added tests to cover my changes.
• I have updated the documentation accordingly.
• I have updated API documentation client/docs/swagger-ui/swagger.yaml

---

This is an automatic backport of pull request #1313 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 0176215 has failed:

On branch mergify/bp/release/v0.48.x/pr-1313
Your branch is up to date with 'origin/release/v0.48.x'.

You are currently cherry-picking commit 01762150b.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   types/coin.go
	modified:   types/coin_test.go
	modified:   x/auth/vesting/types/vesting_account.go
	modified:   x/gov/types/params.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   CHANGELOG.md

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.78%. Comparing base (1f8e902) to head (3209db2).
Report is 8 commits behind head on release/v0.48.x.

Additional details and impacted files

@@               Coverage Diff                @@
##           release/v0.48.x    #1320   +/-   ##
================================================
  Coverage            69.78%   69.78%           
================================================
  Files                  646      646           
  Lines                67507    67525   +18     
================================================
+ Hits                 47109    47122   +13     
- Misses               18212    18215    +3     
- Partials              2186     2188    +2     

Files	Coverage Δ
types/coin.go	95.56% <100.00%> (+0.97%)	⬆️
x/auth/vesting/types/vesting_account.go	87.18% <ø> (ø)
x/gov/types/params.go	5.94% <ø> (ø)

... and 3 files with indirect coverage changes